Fatto d’Archimia Los pigmentos artificiales en las técnicas pictóricas

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MINISTERIODE EDUCACION, CULTURA

Y DEPORTE

Catálogo de publicaciones del Ministerio: educación.gob.esCatálogo general de publicaciones oficiales: publicacionesoficiales.boe.es

Coordinación científica:Marián del Egido

Stefanos Kroustallis

Coordinación de la publicación:Celia Diego

María Domingo

Iolanda Muíña

Corrección de textos:Ana Costalago

Índice

Pág.

Prólogo ........................................................................................................................................................................................... 7

Artificio y artificial: una breve introducción ..................................................................................................................... 9Stefanos Kroustallis y Marián del egido

Fatto d’Archimia: alchemy and artificial pigments .......................................................................................................... 13Mark clarke

Química moderna y producción de nuevos pigmentos ................................................................................................... 25Margarita San Andrés Moya

El color de las palabras: problemas terminológicos e identificación de los pigmentos artificiales................. 53Stefanos Kroustallis

Colores de artificio: comercio y producción en España hasta 1800 ........................................................................... 69Rocío Bruquetas

Las técnicas analíticas de estudio de los pigmentos artificiales: identificación e interpretaciónen obras reales .............................................................................................................................................................................. 83Marisa Gómez

Practical considerations for creating historically accurate reconstructions .......................................................... 105Leslie carlyle

Types of dry-process artificial arsenic sulphide pigments in cultural heritage ................................................... 119Günter Grundmann y Mark Richter

Memory and matter of cultural heritage: lead, tin and antimony based yellow pigments ................................ 145Ulderico Santamaria, Giorgia Agresti y claudia Pelosi

Red Lake Pigments: Sources and Characterisation .......................................................................................................... 157Jo Kirby

El bermellón de Almadén: de Plinio a Goya ...................................................................................................................... 171Rocío Bruquetas Galán

The making of vermilion in medieval Europe: historically accurate reconstructions fromThe book on how to make colours .......................................................................................................................................... 181Maria João Melo y catarina Miguel

Verdigrís. Terminología y recetas de preparación ......................................................................................................... 197Margarita San Andrés, natalia Sancho, Sonia Santos y José Manuel de la Roja

Patrones de identificación del verdigrís: elaboración a partir de la reproducción de recetas antiguas ...... 235Margarita San Andrés, José Manuel de la Roja, Sonia Santos y natalia Sancho

Maya blue studies in relation to history and archeology .............................................................................................. 259Manuel Sánchez del Río

Los azules de cobalto ................................................................................................................................................................ 273Marisa Gómez, Ruth chércoles y Margarita San Andrés

Artificial black pigment. The case of Frankfurter Schwarz / Frankfurt Black / Noir de Francfort / Frankfort Zwart / Negro de Frankfurt ............................................................................................................................... 293Ad Stijnman

7

cennini atribuye la obtención del oropimente, como del bermellón y de otros pigmentos, al resultado de la alquimia. estos pigmentos, que hoy denominamos artifi ciales, han sido fabricados desde la Antigüedad. Algunos ejemplos relevantes son el azul egipcio, utilizado por egipcios y romanos, el albayalde, con gran presencia en la pintura europea desde época medieval, el amarillo de plomo y estaño, desde mediados del siglo xv hasta el xviii, entre otros.

Los procesos de fabricación de los materiales pictóri-cos, las tecnologías asociadas, las impurezas caracterís-ticas de estas sustancias, procedentes de determinadas áreas geográfi cas, son objetivos de investigación por parte del grupo Art Technological Source Research (ATSR) inte-grado en icOM-cc. Muchos miembros destacados de este grupo han aportado, en los últimos años, notables avances en el conocimiento de las técnicas de obtención de estos materiales, y han permitido establecer proce-dencias y relaciones comerciales en diferentes lugares geográfi cos, así como contribuir signifi cativamente a la historia material de los bienes culturales.

Por otra parte, el instituto del Patrimonio cultural de españa, convencido de la necesidad de apoyo a la inves-

tigación y difusión de resultados sobre este tema, y a su importancia para un mejor conocimiento y conservación del patrimonio cultural, ha participado siempre en el apoyo a las aportaciones que los especialistas españoles pudieran hacer al respecto.

este compromiso común inspiró la organización de unas Jornadas Técnicas en 2009, que fueron completadas con otras en 2010, organizadas y fi nanciadas por el iPce, dedicadas a la historia e identifi cación de pigmentos arti-fi ciales en materiales pictóricos. inicialmente, se trataron el bermellón, el minio, el albayalde y el verdigrís, para posteriormente ampliar el elenco a pigmentos azules, amarillos, negros y pigmentos laca.

el éxito de estas jornadas, con participación de los máximos especialistas en cada tema, fueran nacionales o internacionales, permitió comprobar el enorme interés que este tema suscita en historiadores del arte, conser-vadores, restauradores y científi cos de la conservación. esta constatación ha dado como resultado el esfuerzo de recopilación de todas las aportaciones para su publi-cación, como medio que garantiza la pervivencia de lo expuesto y su mayor difusión.

Giallo è un color che si chiama orpimento. Questo tal colore è artifi ciato, e fatto d’archimia

Cennino CenniniIl libro dell’arte, Cap. XLVII

Prólogo

9

Artificio y artificial: una breve introducción

… la técnica, por un lado, ejecuta lo que la naturaleza no puede acabar, por otro, la imita

Aristóteles, Física, ii, 8

el desarrollo de la alquimia y de la química ofreció, a nivel tecnológico, la posibilidad de reproducir sustancias naturales o crear otras nuevas, de acuerdo con las nece-sidades del hombre. Pero además inició, a nivel teórico, un gran debate sobre el propio concepto de lo que es natural y artificial, así como sobre el poder de imitar la propia naturaleza que, hoy en día, sigue todavía vigente1.

el estudio de la fabricación de los colores artificiales sintetiza todos estos aspectos y, además, los traslada al terreno de la creación artística y, aún más, a la conser-vación de los bienes culturales.

Los pigmentos artificiales han sido fabricados emplean-do, en la mayoría de los casos, sustancias naturales a las que se aplicaban altas temperaturas o mediante proce-sos de oxidación y precipitación. en la mayoría de los casos parece que su fabricación se conocía desde la más remota Antigüedad, incluso como curiosidad, debido a su habitual presencia como subproductos del propio proceso de extracción y refinamiento de los metales o de su empleo, intencionado o accidental, en los procedi-mientos técnicos de las llamadas artes del fuego, como la cerámica y el vidrio2.

Las primeras referencias escritas las encontramos ya en los papiros egipcios, las tabletas de barro de las culturas mesopotámicas o en las cortezas de abedul de la india. no obstante hay que señalar que en varios de estos casos se trata de textos médicos que empleaban los pigmentos artificiales también como medicamento

1 Véase Bensaude-Vincent, B.; Newman, W.R. (eds.) (2007): The Artificial

and the Natural: an Evolving Polarity. Boston: Massachusettes Institu-

te of Technology.

2 Moorey, P.R.S. (1994): Ancient Mesopotamian Materials and Industries:

the Archaeological evidence. Oxford: Oxford University Press, p. 327.

o como cosméticos3. ejemplos relevantes son el azul egipcio, el albayalde (blanco de plomo), el bermellón, el cardenillo (verdigrís), el minio, los ocres quemados o la tinta negra ferrotánica.

Por esto, no es de extrañar que en las obras científi-cas o enciclopédicas de la Antigüedad clásica encontre-mos la división entre pigmentos naturales y artificiales bien asentada. Teofrasto ya nos habla de los colores que se preparaban con techne y distinguía, por ejemplo, entre el cinabrio que se encontraba en la naturaleza y el manufacturado (De lapidibus, 55 y 58). También Vitruvio clasificaba a los colores en naturales (tierras, colorantes animales y vegetales) y en artificiales (De Architectura, Vii). no obstante, es en la Historia Natu-ralis de Plinio donde tenemos una clasificación muy detallada de clasificación de los colores y de lo que, técnicamente, se consideraba pigmento artificial. Según el autor los colores se dividen, en primer lugar, en auste-ri y floridi, dependiendo de su grado de luminosidad: los colores austeri son menos luminosos o intensos que los floridi4. Pero aparte de su luminosidad, los colores también se distinguen dependiendo de su origen: … alii nascuntur, alii fiunt; y estos últimos se preparaban a partir de varias sustancias sometidas a tratamien-tos o de varias mezclas (Historia Naturalis, XXXV, 30). no obstante, ambas clasificaciones convergen ya que a los floridi pertenecen los pigmentos naturales, exceptuando el minium, mientras que a los colores austeri pertenecerían casi todos los pigmentos artifi-

3 La estrecha relación entre la alquimia, la materia médica y la tecno-

logía artística; véanse, por ejemplo, Schafer, E.H. (1956): “The Early

History of Lead Pigments and Cosmetics in China”, en T´oung Pao, 44:

413-438; Levey, M. (1962): Medieval Arab Bookmaking and its relation

to early chemistry and pharmacology. Transactions of the American

Philosophical Society, New Series, vol. 52, part 4; Prafulla Chandra Rây,

A. (1956): History of Chemistry in Ancient and Medieval India. Calcuta:

Indian Chemical Society; Campbell Thompson, R. (1934): “An Assyrian

Chemist’s Vademécum”, The Journal of the Royal Asiatic Society of

Great Britain and Ireland: 771-785.

4 Los términos austeri y floridi fueron interpretados de varias maneras,

haciendo hincapié en su luminosidad, su transparencia o su coste (ya

que los floridi los tenía que proporcionar el cliente por su alto precio).

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Fatto d’Archimia

ciales. Parece que Plinio ha sido también la fuente sobre este tema para autores posteriores, como San isidoro de Sevilla (Etymologiae, XiX, 17, 2) o Vincent de Beauvais (Speculum Naturale, Vii, 97), quienes señalan que los colores artificiales se preparan aut arte aut permixtione. esta última frase ha generado, también, cierta discusión al ser interpretada como referencia a procedimientos exclusivamente químicos, en el sentido de que hacían falta procedimientos técnicos y la combinación de varias sustancias, o a pigmentos que se preparaban mediante procesos químicos y físicos, como, por ejemplo, la mezcla de colorantes para obtener otro color. Probablemente, la segunda interpretación sea la más adecuada, ya que a lo largo de la edad Media es ésta la acepción mayoritaria en la literatura artística.

Los tratados de tecnología artística, unas recopila-ciones de recetas con un marcado carácter recordatorio, constituyen una de nuestras principales fuentes para el estudio del arte medieval. este tipo de instrucciones eran necesarias para llevar a cabo procedimientos técnicos que requerían, tanto habilidades por parte del operario, como conocimientos exactos sobre las distintas mezclas de las sustancias y sus características5. no es de extrañar que la mayor parte de su contenido se dedique a la fabri-cación de aleaciones metálicas, de imitaciones de metales preciosos, de vidrios, de gemas artificiales, de la tintura de las pieles y de los textiles, es decir, de gran parte de las artes suntuarias. entre todos estos procedimientos destacan las recetas de los pigmentos artificiales debido a la complicación de su manufactura y de su importancia en las técnicas pictóricas. Al contrario, en muy pocos casos tenemos recetas de fabricación de pigmentos naturales y casi siempre tratan del refinamiento de las materias primas o de información sobre la elección del adecuado aglutinante. Una interesantes referencia sobre la acep-ción del término pigmento artificial en la edad Media la encontramos en la obra De Arte Illuminandi (siglo xiv). Su anónimo autor consideraba que los colores naturales eran los pigmentos de origen mineral, a los que sólo hacia falta refinar y moler; todos los demás eran los artificiales: es decir, todo tipo de pigmento producido por cualquiera

5 El anónimo autor del tercer libro del Tratado de Heraclio (s. xiii) señala-

ba que, a parte de las consideraciones teóricas respecto a los colores

y otros aspectos de la pintura, el artista debía tener siempre el nece-

sario conocimiento práctico de los materiales y de sus características:

“… in arte pictoriae, ultra debitas considerationes quantum ad colorum

varietates, ac eorum et aliarum rerum in ipsa arte concurrentium diffe-

rentias”, en Merrifield, M. (1967): Original tres dating from the xiith to

xviiith centuries on the Arts of Painting, vol. I. New Cork: Dover, p. 255.

tipo de transformación química (combustión, fundición, aleaciones metálicas, etc.) como el cinabrio, el minio, el blanco de plomo, el blanco de cenizas o el verdigrís; o por cualquier tipo de proceso físico (maceración, preci-pitación, etc.), como los pigmentos laca de colorantes vegetales como cúrcuma, rubia, espino de los tintoreros, los lirios azules o el tornasol ( folium)6.

el contemporáneo cennino cennini en su célebre obra Il libro dell’arte nos ofrece una acepción del término artificial un poco distinta. en el capítulo XXXVi describe los pigmentos naturales, su clasificación se basa tanto en el color como en el método de fabricación. cennini afirma que hay siete colores naturales, de los cuales cuatro son de naturaleza terrosa (negro, rosso, giallo e verde) y otros tres colores naturales (bianco, azzurro oltremarino o della Magna e giallorino) pero que necesitan aiutare artifizialmente. Según el autor, el término artificial se puede aplicar también a los pigmentos que son el resul-tado de una reacción química pero de manera natural, geológica, como es el caso del giallorino (cap. XLVii). Al contrario, los que fabrica el hombre, son llamados fattos d´archimia, como el cinabrio (cap. XL), el minio (cap. XLi) o el oropimente (XLVii). es obvio que el autor no se refiere realmente a la alquimia en la que participa el hermetismo como doctrina filosófica, tal como se entiende en la historia de la ciencia, sino como producto del uso de retortas, hornos, crisoles y utensilios de laboratorio propios de la tecnología química7. el uso de este método de fabricación es el que hace atribuir a cennini la natu-raleza alquímica de los pigmentos, como el oropimente, el bermellón, el verdigrís o el blanco de plomo.

esta división de los pigmentos ha sido repetida de manera constante en la mayor parte de los tratados artís-ticos a lo largo de los siglos, aunque no siempre se ha empleado la misma nomenclatura. Por ejemplo, Palomino divide los colores en minerales, es decir, los que produce la naturaleza por su propia virtud y artificiales, es decir, los que se forman con beneficio del ingenio y del arte8.

La revolución científica del siglo xviii supuso un gran aliciente para la fabricación y uso de los pigmentos arti-ficiales, ya que, aparte del número cada vez mayor de pigmentos disponibles en el mercado, también comenzó

6 Brunello, F. (1992): De arte illuminandi e altri trattati sulla tecnica della

miniatura medievale. Vicenza: Neri Pozza, pp. 38-43.

7 Pérez Pariente, J.; López Pérez, M. (2005): Alquimia: ciencia y pensamiento

a través de los libros. Madrid: Universidad Complutense de Madrid.

8 Palomino de Castro y Velasco, A. (1795): El museo pictórico y escala

óptica, libro I, p. 30. Madrid: Imprenta de Sancha.

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Artifi cio y artifi cial: una breve introducción

su producción industrial, no necesariamente relacionada con fi nes artísticos9. desde fi nales del siglo xviii y a lo largo del siglo xix, se fundan las nuevas industrias de pigmentos, como Lefranc en Francia o Winsor & newton en inglaterra, dedicadas no sólo a la fabricación y comercialización de sus productos, sino también a la investigación para encontrar nuevos pigmentos o diferentes gamas de colores. ejem-plos característicos son el azul de Prusia, descubierto por accidente en 1704, o el malva de Perkins, descubierto en 1856, que es además el primer tinte de anilina. A nivel terminológico, todos estos aspectos se refl ejan también en la sustitución del término “artifi cial” por el más adecuado o moderno, en este momento, “sintético”. Además, en varios casos, los nuevos pigmentos seguían conservando su nombre histórico aunque, a veces, su composición no tenía nada que ver con el pigmento original. Todos estos cambios en la producción de los pigmentos y las posibi-lidades que ofrecía el desarrollo de la química ha hecho que, en la actualidad, el concepto de pigmento artifi cial haya cambiado sustancialmente, ya que no se emplea tanto para hacer referencia a su método de manufactura sino para defi nir el color resultante: una mezcla de los colores principales y, sobre todo, de los colores que no se ven en la naturaleza.

Otro aspecto interesante respecto al uso de los colores artifi ciales es que, a lo largo de la historia de su fabricación, se han considerado siempre como opuestos a los pigmen-tos naturales, si bien preparados con el fi n de imitarlos. el poder imitar a la naturaleza mediante artifi cio es un locus communis en varios autores desde la Antigüedad. citare-mos sólo a Alonso Barba que, en su célebre obra Arte de los Metales, incluía los pigmentos artifi ciales en las cosas metálicas artifi ciales y señalaba que así se podía imitar la hermosura de la naturaleza10. Precisamente esta posibili-dad de imitar a la naturaleza ha generado también cierta controversia, al considerar que, el hecho de poder imitar sólo la apariencia, podía conducir al engaño, por lo que el término artifi cial ( facticio) se hizo también sinónimo de doloso y fraudulento, al igual que el trabajo de los alqui-mistas. no obstante la diferencia entre la falsifi cación y la imitación es la intención de engañar, aunque también hay que señalar que este concepto estaba mucho más claro en la mentalidad de las clases educadas. Según San isidoro de Sevilla (Etym., ii, 267 y 382), la imitación no era una mera

9 Es cierto que algunos pigmentos se producían a gran escala desde el

siglo xvii como, por ejemplo, el verdigrís en Montpellier, pero se trata-

ba de manufacturas con un marcado carácter de empresa familiar y

no industrial.

10 Barba, A. (1640): Arte de los metales. Madrid, Imprenta del Reino, p. 62.

copia material, sino una prolongación de la actividad de la naturaleza: el hombre observaba cuáles eran las leyes que permitían a la naturaleza alcanzar ciertos resultados y siguiendo estas leyes se esforzaba, mediante su trabajo, en obtener resultados análogos. También San Agustín diferen-ciaba entre el engaño que busca el placer (mendacium) y el que busca conseguir efectos serios ( fallacia)11.

La publicación del presente libro es el resultado fi nal de las jornadas técnicas Fatto d´archimia: Historia e Identifi ca-ción de los Pigmentos Artifi ciales en las Técnicas Pictóricas organizadas por el grupo de trabajo del icOM-cc Art Technological Source Research y el instituto del Patrimonio cultural de españa (2009, 2010). el principal objetivo de estas jornadas era el estudio de la fabricación y del uso de los cuatro pigmentos artifi ciales más importantes en las técnicas pictóricas europeas, desde la Antigüedad hasta, prácticamente, el siglo xix, con el fi n de fomentar las inves-tigaciones interdisciplinares entre los distintos campos de estudio dedicados a la historia y a la conservación del patri-monio artístico en españa. Por esta razón, la publicación del presente volumen pretende ofrecer una metodología de aproximación e interpretación de las tres fuentes principa-les para este tipo de investigaciones: 1) las fuentes escritas (documentos, contratos, tratados de técnicas artísticas, etc.); 2) los resultados de los análisis de laboratorio (identifi cación de los pigmentos en obras reales y su interacción con el resto de los materiales); y 3) la reconstrucción de las recetas antiguas que explican la fabricación de estos pigmentos, con el fi n de comprobar su validez y averiguar su relación con la praxis artística coetánea.

Los responsables científi cos de este libro quieren agra-decer el apoyo, institucional y fi nanciero, del Ministerio de educación, cultura y deporte a través del instituto del Patrimonio cultural de españa. en particular, de su direc-tor Alfonso Muñoz, que ha apoyado la materialización de esta iniciativa, y de los esfuerzos realizados por el área de documentación y difusión del iPce, encabezado por María domingo, para que esta publicación fi nalmente vea la luz.

Stefanos Kroustalliscoordinador del grupo del trabajo del icOM-cc Art Technological Source Research

Marián del egidoJefe de área de Laboratoriosinstituto del Patrimonio cultural de españa

11 Bruyne, E. (1987): La estética de la Edad Media. Madrid: Visor, p. 59.

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Fatto d’Archimia: alchemyand artificial pigments

Mark ClarkeUniversity of Amsterdam

mark@clericus.org

Resumen

el capítulo analiza los antecedentes del descubrimiento y de las primeras manufacturas de los pigmentos sinté-ticos inorgánicos y, además, describe lo que significaba “alquimia” para los pintores en la baja edad Media o comienzos del Renacimiento.

en la primera parte se describe la historia y los prin-cipales métodos de fabricación de pigmentos artificiales, desde el período Paleolítico hasta c. 1500.

en la segunda parte se habla del género del libro de recetas de los artistas, se esboza su desarrollo desde c. 700 hasta c. 1500 y se explica su naturaleza, contenido, métodos de composición, interpretación y uso.

en la tercera parte se examina la relación entre la práctica del taller frente a la tradición textual. Se discuten las razones por las que los libros de recetas no siempre reflejan con precisión las prácticas contemporáneas de un taller, teniendo en cuenta las preguntas de quiénes fabricaban pigmentos y el porqué, y quiénes escribían estos textos técnicos y el porqué. Parece que una de las razones se encuentra precisamente en los diferentes tipos de alquimia: práctica, filosófica y médica.

La principal conclusión del estudio es que la gran mayoría de los manuscritos medievales que contienen

recetas artísticas son textos precisos y fiables. Aunque hay que tener siempre presente el papel de la alquimia y su relación con los tratados escritos por artistas así como con las prácticas de taller, estos recetarios artís-ticos se pueden emplear, en gran medida, como guías prácticas. en definitiva, cuando el término Archimia se aplicaba a los pigmentos simplemente significaba una “síntesis química”.

Palabras clave

Alquimia, pigmentos artificiales, libros de recetas, prác-tica de taller, tradición textual.

Abstract

This chapter looks at the background to the discovery and manufacture of early synthetic inorganic pigments, and describes what “alchemy” meant to a late-mediae-val or early-renaissance painter.

Part i outlines the history and main methods manu-facture of artificial pigments, from the Palaeolithic period to c. 1500.

Part ii introduces the genre of artists’ recipe books. it outlines their development from c. 700 Bc to c. 1500.

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Fatto d’Archimia

it introduces their nature, content, methods of compo-sition, interpretation and use.

Part iii considers the relationship between work-shop practice versus textual tradition. Reasons that recipe books may not always accurately reflect contem-porary workshop practices are discussed, based on a consideration of who made pigments and why, and who wrote recipe texts and why. One reason is found to be the different types of alchemy: practical, philo-sophical, and medical.

it concludes that the great majority of mediaeval manuscripts containing artist’s recipes are accurate and reliable. While we need to be aware of the role of alchemy and its relationship to artists’ written texts and workshop practices, we can largely rely on those texts as practical guides. “Archimia” (where applied to pigments) was simply “synthetic chemistry”.

Keywords

Alchemy, artificial pigments, recipe books, workshop practice, textual tradition.

Introduction

Around 1400, the Tuscan painter cennino cennini described the manufacture and preparation of numer-ous pigments in Il libro dell’arte. For some pigments he gave no recipes for the artist to use, but simply stated that they were fatto d’archimia, “made by alchemy”, and recommended that the artist should not waste time trying to learn how to make these pigments, but instead recommended that the pigments should be bought ready-made at the apothecary.

This chapter will look at the background to the discovery and manufacture of early synthetic inorgan-ic pigments, and will describe what “alchemy” meant to a late-mediaeval or early-renaissance painter.

it has been said that “The medieval alchemist discovered new colors by accident”1. This is wrong. Admittedly certain materials used as pigments were not specially invented or developed for use as pigments, but were originally developed for other uses, for example as by-products of procedures for making non-paint artefacts, or as by-products of (successful or

1 Kurt Wehlte, The Materials and Techniques of Painting. Translated by

Ursus Dix. New York: Van Nostrand Reinhold Company, 1975.

failed) attempts to make other materials. But neverthe-less Man has made artificial pigments quite deliberate-ly, starting in pre-historic times2.

Part I: The antiquity of artificial pigments

Let us briefly review how more and more artificial pigments were introduced with time. Our knowl-edge of the dates of introduction of most pigments is very approximate. Throughout history, the tenden-cy is that new materials supplement old ones, and old ones continue to be used. exceptions are the egyptian manufactured pigments, egyptian blue (which disap-peared and reappeared later as naples yellow) and the classical shellfish dye Tyrian Purple which apparently disappeared after the fall of Byzantium in 1453.

Palaeolithic Man

Painting –and therefore the use of pigments– dates from the Palaeolithic period, with european parietal art surviving from at least 32.410 before present. Some pigments have remained largely unchanged since their ancient origins. Since Palaeolithic times earth pigments (surface or mined minerals) have always been abun-dant and cheap, and available in similar forms all over the world. They are iron and manganese ores. Ochres and Siennas vary from yellow to brown to red (haem-atite), and the colour is derived from iron (iii) hydrox-ides and iron (iii) oxides. Umbers are aluminium sili-cate clays, coloured by hydrated iron (iii) Oxide, and again provide a range of red-browns and yellows.

earth pigments need to be ground for use. By clas-sical times they were purified by washing. Some may be used with little or no refining, e.g. the siliceous clay terre verte. Others need to be ground and purified by washing before use. Purification is carried out by “levi-gation”. The ground raw material is stirred up in a water bath; the sand settles out fairly quickly, and humus and other vegetable matter floats and may be skimmed off. The suspension of pigment particles is drained off, and allowed to settle. The largest pigment particles settle first. This process may then be repeated to sort particles into

2 A pigment is the part of the paint which gives it its colour. Strictly speaking

a pigment is a finely divided particle which is insoluble in the paint medium,

as opposed to a dye or stain, which is soluble in the medium, but for conve-

nience when talking about paint we may call them both pigments.

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Fatto d’Archimia: alchemy and artifi cial pigments

batches by size; this is useful for certain pigments for which the colour and intensity varies with particle size.

Pre-historic wall paintings mainly use natural ochres, but also black magnetite shaped into “crayons” have been found from 17.000 ago3. The other Palae-olithic pigments are black manganese oxide, carbon black and chalk white. The earliest “man-made” pigment could be said to be charcoal, burned wood. (it is the use of this organic black on wall paintings that allows the paintings to be carbon-dated.) But even if we exclude charcoal, Palaeolithic man was neverthe-less modifying natural materials to make pigments at least 10.000 years ago. The exact colour of many earth pigments depends on the state of hydration. even in 10.000 before present artists heated pigments to produce a different colour, heating yellow goethite to around 250-300° c to produce red haematite4.

Ancient Egypt

egypt, from c. 4000 Bc, used the same pigments as were used in the Palaeolithic period, plus some new ones, namely the crushed mineral colours natural red cinnabar (mercury ore), the two related pigments natu-ral orpiment (yellow) and natural realgar (red) which are both arsenic sulphides, and the two forms of basic copper carbonate green malachite and blue azurite (found together in copper mines and gold mines).

Once metals had begun to be used, people natu-rally would have noticed corrosion products. Appar-ently beginning in egyptian times, the use of coloured corrosion products as pigments began, and by clas-sical times they were in widespread use. The most important are lead white (basic lead carbonate) and verdigrís (basic copper acetate). not only were these coloured corrosion products used as pigments, but it seems they were deliberately manufactured. They were made by suspending strips of sheet lead or copper over vinegar in sealed pots, which were placed for warmth in dung piles, and left. For verdigrís grape skins could be used instead of vinegar.

We have seen that Palaeolithic man modifi ed existing materials (burnt ochres) and that the egyptians deliber-

3 Chalmin et al., “Minerals discovered in Paleolithic black pigments by

transmission electron microscopy and micro-X-ray absorption near-

edge structure”, Applied Physics A, 83.2 (2006): 213-218.

4 Pomiès, M.-P., M. Menu and C. Vignaud (1999): “Red Palaeolithic Pigmen-

ts: Natural Hematite or Heated Goethite?”, Archaeometry, 41:2, 275-285.

ately encouraged the formation of natural corrosion (lead white and verdigrís). But the egyptians were also the fi rst to make whole new pigments, rather than copies, modi-fi cations or refi nements of naturally occurring materi-als. We fi nd in the egyptian palette the fi rst truly new synthetic pigments: blue frit (copper-containing ground glass from c. 2500 Bc), lead antimonate yellow (from c.16 century Bc), white gypsum (from burned lime), and later (in the Ptolemaic period) madder lake pigments (see below). it appears that while the egyptians used indigo as a dye, they did not use it as a pigment.

Classical Greece and Rome

The classical palette was largely the same as the egyp-tian, plus dragons-blood (a red plant resin), “minium” (red lead), terre verte (green earth), weld yellow lake (plant, cennini’s arzica), kermes red lake (insect), madder red lake (plant), and Tyrian purple lake (shell-fi sh secretion).

it is in the late classical times that synthetic versions of natural products began to be made: cinnabar, orpi-ment, minium. Often the starting point was the natu-ral product, but the resulting pigment had colours that were more pure and intense than the natural products. This manufacture of man-made inorganic pigments continued through the mediaeval period, and to the present day. it is especially these that cennino refers to as fatto d’archimia.

Mediaeval Europe

While known to the egyptians and Romans as a stone, ultramarine was not apparently used by them as a pigment, but it was the mediaeval blue pigment par excellence, fi rst identifi ed in northern europe paint c. 1000. it was extre-mely expensive, since it required complex purifi cation, and because it appears that, although it is now found in Siberia and even italy, apparently the main or even the only source exploited in the middle ages was in Afghanistan.

Mediaeval innovations seem to have been bone white (calcined bones, useful as it is not degraded by contact with orpiment or other chemically aggressive pigments), the widely-used import brazil (red dye from an indian wood), and the blue ultramarine.

it is also in the mediaeval period that we see the expansion in the use of lake pigments. Lake pigments are where the study of artists’ pigments overlaps that of textile dyes. A lake is a dye that has been attached to a colourless inert substrate, such as chalk or gypsum. First

16

Fatto d’Archimia

a “lye” (alkali) is made from a suitable material such as wood ash (potassium carbonate) or stale urine, (urea decomposes to give alkaline ammonia). A lye solution may be used to extract the dye from cloth, as appears to have been the case for early insect lakes. This means it is not necessary to have access to the raw materials, and imported cloth might be used. Alternatively the lye is added to a vat filled with dye. An alum solution (which is acidic) is added, and a precipitate of insoluble aluminium hydroxide forms, which is colourless, but which becomes coloured by the adsorption and absorption of the dye. it is thought that the origins of lake pigments lie in the scum scraped from the top of a dye bath: this would be an insoluble salt resulting from an alkaline dye bath and an acidic alum mordant. Alternatively, calcium carbonate (as chalk or marble dust) or gypsum was immersed in a dye-bath and coloured by adsorption. Many dyes could also be used in this way as pigments, and the study of dyes is therefore relevant to the study of pigments.

The most important mediaeval lakes were the plant-dye lakes madder red (especially from the species “wild madder” Rubia peregrina and “dyer’s madder” Rubia tinctorum), weld yellow (Reseda luteola) and brazil-wood red (Caesalpina species of trees), and lakes made from the red dyes obtained from insects: kermes, carmine, and lac (from Kermes species, Porphyrophora species, and Kerria lacca respectively). Another mediaeval innovation for illuminators was the “clothlet” colour: pieces of rag dipped in the coloured juice of various plants. When they were required for use, a piece was put into a shell, and a little painting medium was poured over it; then it was stirred about until the colour was discharged. dyes and stains were also used early on for painting as were clothlets. coloured plant material (e.g. saffron, Crocus sativus L.) could be placed directly into the medium, and allowed to stain it. This paint could be allowed to dry in some container such as a shell, and used as a watercolour. indigo (from woad, Isatis tinctoria L., or from imported indigo, Indigofera species) may have been used perhaps ground as a pigment or perhaps as a lake. The red resin dragonsblood (from trees Pterocarpus draco L., Dracaena draco L.) was also known and apparently used. Recently it has been confirmed that –very rarely–  the classical “Tyrian” or “imperial” purple dye (extracted from various species of shellfish) was used in manuscript painting5.

5 Cheryl Porter, cited in: M. Clarke, “Anglo-Saxon Manuscript Pigments”,

Studies in Conservation, 49.4 (2004): 231-244; which see also for the

earliest identifications of ultramarine pigments.

Part II: Artists’ recipe books

One of the most important sources of information we have about the manufacture of early artists’ materi-als at different periods is contemporary written “reci-pe books”. Over 450 medieval manuscript volumes containing artists’ technical instructions and recipes have been identified6. Mediaeval artists’ recipe texts consist mainly of instructions for the manufacture of materials: pigments, inks and painting media. Some also describe the preparation of supports, such as panel assembly and priming, or parchment manufac-ture. Recipes particularly concentrate on preparation of paints and inks starting from the raw materials, including the selection and testing of materials, refin-ing, grinding, and mixing of pure materials, and the manufacture of synthetic materials and compounds such as ink, verdigrís and white lead. Some describe suitable mixtures, in particular which medium is best suited to which pigment and which pigment may be mixed with which other. They also warn of unsuita-ble mixtures of pigments, i.e. combinations that are chemically unstable, resulting in discolouration. The use of gold and its imitations was also clearly a wide-spread preoccupation, especially for scribes. A small number also describe pictorial technique such as the choice of colour for hair or beards, or modelling tech-niques for flesh and drapery in which highlights and shadows are composed from prescribed mixtures of pigments.

Treatises and Compilations

coherent extended treatises (such as those by Theophilus or cennino cennini) are the minority. The majority are anonymous collections of short reci-pes, some of which are organized thematically, others of which have clearly accumulated more randomly. While there are a number of distinct unique and indi-vidual texts, there was also a considerable influence of a few particular texts that survive in multiple copies and in extracts. Many mediaeval recipe treatises are compiled from earlier manuscripts.

6 For a fuller overview and catalogue of these, with a bibliography of

their editions, translations, and commentaries, see M. Clarke, The Art

of All Colours: Mediaeval recipe books for painters and illuminators

(London: Archetype Publications, 2001).

17

Fatto d’Archimia: alchemy and artifi cial pigments

Assyrian recipes

The earliest technical recipes that survive are Mesopo-tamian Assyrian cuneiform texts for making coloured vitreous material (opaque glass or ceramic glaze). These date from the seventh century Bc, from which period also survive recipes for dyeing wool and for cooking food. These Mesopotamian recipe texts are very brief, being little more than lists of ingredients, with very little explanatory material.

Classical references

The earliest references to the materials and practices of painters and scribes are classical. These, however, are not recipes exactly, but rather descriptions of mate-rials, techniques and processes. Theophrastus (370-288 Bc) describes various pigments and their prepara-tion. in the fi rst centuries Bc and Ad survive technical descriptions by Vitruvius (in the context of wall paint-ing), Pliny (in his general encyclopaedia) and diosco-rides (as Materia Medica). With the likely exception of Vitruvius, these authors were not practicing craftsmen, and as a result the quality of the descriptions is variable.

Hellenistic Egypt

The fi rst post-classical recipes per se are found in the Leiden Papyrus X7, and the Stockholm Papyrus8, written in Greek, coming from egypt, and dating from c. 300 Ad. These mainly deal with the imita-tion of precious and sumptuary materials, that is the “improvement” and imitation of gold, silver, Tyrian purple dye, and gems. Leiden Papyrus X is especially of interest to historians of manuscript art as it contains recipes for writing in gold and in silver. The recipes in the papyri are similar in form to the Assyrian exam-ples, being concise, with little explanatory material.

Early mediaeval European recipe manuscripts

next chronologically comes a family of related compi-lation manuscripts the most important and complete examples being the late eighth century Lucca manu-

7 Leiden, Rijksmuseum van Oudheden, Papyrus P. LEID. X, Museum cata-

logue n.º I 397, inventory number A.MS 66 = P. Lugd. Bat. J.397 (X).

8 Stockholm, Kungliga Biblioteket, Handskriftsavdelningen, Dep. 45. P.

HOLM = Papyrus Graecus Holmiensis.

script (also known as the Compositiones ad tingenda and as the Compositiones variae)9, the 9th-12th century Mappae clavicula10, and the c. 1130 Codex Matriten-sis11. These compilations contain recipes for a number of crafts including metalwork, dyeing, and mosa-ic, and including several recipes relevant to paint-ing. The core of this substantial collection of recipes (about 300) was probably originally compiled around 600 Ad, perhaps in Alexandria, and contains items traceable to earlier classical texts and to the aforemen-tioned papyri12. Many mediaeval manuscripts contain-ing collections of recipes include extracts from this family of recipes. Often found in combination with the Mappae clavicula family of manuscripts, but also found elsewhere, both independently and attached to other texts, is the anonymous De coloribus et mixtion-ibus, perhaps originating c. 110013. There also survive a number of other useful early mediaeval recipe texts all with similar formats: short practical recipes, mainly concerned with materials, written in Latin. Also from c. 1100 survives a new and non-derivative text, that of Theophilus14. This systematic treatise treats paint-ing and illuminating, as well as glass and metalwork. Theophilus differs from the majority of early medi-aeval recipe texts in that he also describes pictorial technique, e.g. modelling of fl esh, hair, and drapery. extracts from Theophilus then themselves entered the text stream and appear in compilations15.

9 Lucca, Biblioteca Capitolare Feliniàna, Codex 490, ff . 211v, 217r–231r.

10 The most commonly cited manuscripts are Corning (New York State),

Corning Museum of Glass, MS 5, 12th century, and Sélestat, Biblio-

thèque Humaniste MS 17, 9th-10th century.

11 Madrid, Biblioteca Nacional, MS A.16, ff . 199–203. S. Kroustallis, Edición

crítica y estudio de un tratado medieval de tecnologia artistica: Codex

Matritensis 19, unpublished PhD dissertation, Universidad Compluten-

se de Madrid (2005).

12 Clarke, Art of All Colours, p. 9.

13 Clarke, Art of All Colours, pp. 9-10.

14 De diversis artibus. There are four relatively complete manuscripts

(London, British Library, MS Egerton 840A and MS Harley 3915; Vien-

na, Österreichische Nationalbibliothek, MS 2527; Wolfenbüttel,

Herzog-August Bibliothek, Cod. Guelph. Gudianus latinus 69 2° [= cat.

4373]), and a great number of fragments.

15 The degree of technical knowledge varies considerably between

sections, and dating the treatise exactly is very diffi cult, with much

apparently contradictory evidence. I have recently argued that the text

of “Theophilus” was in fact compiled by various people.

18

Fatto d’Archimia

Later Mediaeval recipe books

The majority of surviving mediaeval recipe manu-scripts date from this period. (Less than 40 manuscripts survive to c. 1300, and less than 40 survive from the thirteenth century, but over 100 from fourteenth and over 250 from the fifteenth). The more substantial exam-ples of the texts include the Liber de coloribus illumi-natorum siue pictorum (illuminating)16, De arte illu-minandi (illuminating)17, Likneskjusmith (polychrome sculpture)18, Pseudo-Savonarola (mainly pigments)19, the Strasburg Manuscript (illumination and miniatures)20, the Livro de como se fazem as cores21 Archerius/Alcherius (three texts)22, Tractatus qualiter quilibet artificalis color fieri possit23, the compilation of Le Begue24, Montpelli-er Liber diversarum arcium25, cennino cennini Il libro dell’arte (a systematic treatise)26, the Segreti per colori or Bolognese manuscript (a systematic collection)27, Ambri-gio’s Ricepte d’affare più colore28, the Göttingen Model-book29, and (less known) the Hastings manuscript (a “housebook”)30, and numerous anonymous and various texts entitled de coloribus.

The emphasis of recipe books alters after c. 1300. in general the later manuscripts are more concerned with technique (mixtures, tempering and modelling) and less concerned with manufacture of materials (e.g. making

16 London, British Library, MS Sloane 1754.

17 Naples, Biblioteca Nazionale Vittorio Emanuele II, MS XII.E.27.

18 Copenhagen, Arnamagnean Institute, MS AM 194.8.

19 Ferrara, Biblioteca Comunale Ariostea, MS Cl. II. 147.

20 The original manuscript was destroyed by fire; a nineteenth century

transcription survives at the National Gallery London.

21 Parma, Biblioteca Palatina, MS De Rossi 945. (Recently re-dated to the

fifteenth century).

22 Paris, Bibliothèque Nationale, MS latin 6741, ff. 81v–86v.

23 Paris, Bibliothèque Nationale, MS latin 6749B.

24 Paris, Bibliothèque Nationale, MS latin 6741.

25 Montpellier, Bibliothèque de la Faculté de Médicin, MS 277. Edition,

English translation, and commentary by M. Clarke: Mediaeval Painters’

Materials and Techniques: The Montpellier ‘Liber diversarum arcium’.

London: Archetype Publications, 2011.

26 The pre-c. 1500 AD manuscripts of which are Firenze, Biblioteca Medi-

cea-Laurenziana, MS XXIII plut. 78, and Firenze, Biblioteca Riccardia-

na, MS 2190.

27 Bologna, Biblioteca Universitaria, MS 1536.

28 Siena, Biblioteca Comunale degli Intronati, MS I.II.19.

29 Göttingen, Niedersächsische Staats- und Universitätsbibliothek,

Codex 8˚ Uff. 51 Cim.

30 San Marino California, Henry E. Huntington Library, MS HU 1051.

synthetic pigments), which were by now readily availa-ble for purchase. That said, the preparation and use of more new organic pigments are described than befo-re (and also more recipes for existing ones). Fewer late mediaeval manuscripts are principally or entirely copies of earlier texts (such as Theophilus, Heraclius, and the Mappae clavicula), and there is a corresponding increase in the proportion of newly composed texts, which we may assume are more likely to reflect current workshop practices and original observations. Later texts are also more commonly written in the vernacular, not in Latin. Vernacular manuscripts mostly appear to contain new material, and it seems very likely that many of these were composed from original observation.

Part III: Workshop practice versus textual tradition

Who made pigments and why?

clearly artificial pigments have been made by Man for thousands of years, using minerals, metals, plants, shell-fish and insects as raw materials. cennini gave recipes for some of these. The pigments cennini said were fatto d’archimia, “made by alchemy”, were cinnabar, minium, orpiment, arzica, verdigrís, and lead white. What did cennini mean when he specified that these were “made by alchemy”?

First of all it is important to realise that painting was only one use of these materials. “Pigments” were also used for colouring ceramics and for cosmetics, (lead white and even arsenic was used until the eighteenth century) and even for cooking (lead white was used to sweeten Roman wine). Refinement and new development was needed for these other uses, and the painters benefited. Some of the new synthetic pigments were by-products of other industries or crafts, for example egyptian blue (a by-product of glass craft) and lead antimonate yellow (of ceramic craft).

But the most important use of most pigment mate-rials until the eighteenth century was medicine. Until the nineteenth century many painter’s materials were bought at the apothecaries, either raw or somewhat prepared, partly because the apothecary was the usual supplier of small high-value materials, and partly because many of what we consider to be artist’s materials were also at that time used as medicines. This why cennini, for example, wrote that vermilion could be bought at the apothecary (speziali). indeed, in mediaeval times doctors

19

Fatto d’Archimia: alchemy and artifi cial pigments

and painters were closely related. St Luke was described in the Bible as a doctor, and in the mediaeval period it was widely believed that he had painted a portrait of the Virgin Mary; in consequence the guild of St Luke in certain towns included both doctors and painters. indeed, a number of doctors wrote about artists’ practices, such as de Ketham, de Mayerne, and Agricola. Apothecaries would serve both types of customer. Many raw mate-rials were common to medicine and art, and were to be found together in dispensaries and apothecaries, and in consequence their recipes are often found together.

The reliability of recipe books

How reliable are recipe manuscripts as a guide to the workshop practices of their contemporaries? Mediae-val artists’ recipe manuscripts seem plausible. However recipes were also sometimes transmitted simply as liter-ary texts, for the “general reader”, not for artists. Many of these “literary recipes” are found transmitted along-side recipes and texts on alchemy and medicine, rath-er than alongside texts on pictorial arts. in the mediae-val period scholarship was to a great extent concerned with preserving ancient texts, and so one of the greatest problems in studying mediaeval artists’ recipes is trying to determine when a text was transmitted independent-ly from workshop practice.

i suggest that two types of re-working and re-use of technical texts took place in the middle ages.

The fi rst practical type of reworking would consist of removing rhetoric, adding further technical informa-tion (whether from other recipe books or from person-al experience), and making small modifi cations to the existing recipes (for example to substitute local mate-rials for unfamiliar or unobtainable ones, an attest-ed practice in medical recipe manuscripts), to alter timings or quantities to conform with local systems of measurements and weather, and to record personal technical improvements and tricks of the trade. Good examples of texts that have been re-worked to make them more practical are the Montpellier Liber diversa-rum arcium31 and the related Brussels Compendium Artis Picturae32.

But equally clearly there was a second type of reworking, in which a text was made less suitable for the workshop. This second type of reworking

31 See note 25 above.

32 Brussels, Royal Library, MS 10152.

produced a text that was not intended for craft prac-titioners but for “general readers” and patrons. This reworking resulted in a text that was essentially a liter-ary production divorced from the workshop, with a consequent loss of technical accuracy. Such “literary” copies are the source of numerous problems in artists‘ recipe research. They were particularly prone to textu-al corruption and accumulated ever more tangential-ly connected material, usually rather impractical and theoretical, and so have featured prominently in nega-tive opinions on mediaeval technical recipes.

The coming of print also tended to preserve reci-pes indiscriminately, without reference to workshop practices. early printing was not so much concer-ned with the publication of newly composed texts, but rather with reproducing existing ones in greater numbers than before. in the early days of printing textual corruption actually increased. With print the availability of texts allowed the student or apprenti-ce to overtake the knowledge of the master, and made lay advancement possible, even outside the professi-ons or guilds.

Magic in recipes

This question of the relationship between workshop and recipe texts raises the question of magic. House-hold recipes and especially medical recipes often contain an element of magic, e.g. the time or manner of collecting plants or the employment of magic words, and ritual. Mediaeval magic can perhaps be distinguished from mediaeval science by its results not being direct and inevitable, but requiring a magi-cally prepared operator (it can not always simply be learned), and by its working being hidden, i.e. “occult”.

However we must be careful of too quickly attrib-uting a feature of a recipe that seems to us to be point-less, to magic or ritual. consider the vermilion reci-pe in the Livro de como se fazem as cores, chapter 15, which states that the mercury and powdered sulphur should be mixed “always stirring it with a dog’s foot that has its hair and wool”. Abrahams considered this to be “technological superstition”33. But mixing these two ingredients, one mobile and cohesive and the other powdery, is diffi cult; reconstructions by catari-na Pereira Miguel demonstrated that a woolly-textured

33 H. J. Abrahams, “A Thirteenth-Century Portuguese Work on Manus-

cript Illumination…”, Ambix, 26 (1979), 93–9.

20

Fatto d’Archimia

mixing implement helps significantly in combining the ingredients.

Another explanation has been proposed for appar-ently “impossible” recipes such as Spanish Gold34, carving crystal with goat blood35, or the less-flamboy-antly magical but still chemically impossible silver-corrosion blue or mercury blue. Spike Bucklow has been argued that these recipes are in fact in accord-ance with mediaeval scientific paradigms (for example the “fire” of goat blood opposing the “water” of crys-tal), and furthermore has argued concerning silver-blue that the recipe may indeed have been impossi-ble, but that it filled a gap in a theoretical system of coloured “rusts”, i.e. it was a gedanken experiment.

Artists’ recipe books are largely free of magic. They are not, however, devoid of a spiritual or mystical element. They are also not devoid of alchemy. certain recipes that appear at first to be for artists’ materials, are in fact alchemical36. Furthermore, often artists’ recipes are found in manuscripts that otherwise contain mainly alchemy.

Artists’ colour recipes and alchemy

What was alchemy? The common view is that it was  proto-chemis, contaminated or dominated by madness: mystical and magical, with mad symbols, mad drawings, mad people doing things that had no relation to the real world.

Alchemy, however, was not magic. A more sophis-ticated view is that there were two forms: practical alchemy (the true ancestor of today’s practical chem-istry) and theoretical alchemy (a theoretical dead-end, with no relation to modern chemical theory). certain alchemists were probably primarily chemical produc-ers, e.g. apothecaries. They could have functioned with tried and tested recipes, and would not necessarily require any theoretical knowledge. Alongside them was a second type of alchemy that was more theoretical.

Alchemy appears to have started in Hellenistic Alexandria, where the cultures of classical Greece, Rome, egypt, Mesopotamia, and the Middle east were blended. Scientific thought, mysticism and technolo-gy became combined in new and long-lasting ways.

34 Theophilus I.48: “There is also a gold named Spanish gold, which is

compounded from red copper, basilisk powder, human blood, and

vinegar”.

35 Theophilus I.95.

36 Clarke, Art of all Colours, 35-39.

The distinguishing feature of alchemical, as opposed to technical, texts isin consequence the combination of spiritual and practical37. The physical and metaphysi-cal worlds were seen as closely related. Physical objects had hidden relations of sympathy and marvellous powers, and possessed philosophical properties. Aris-totle considered natural phenomena were comprehen-sible by reason alone, but to many thinkers in Hellenis-tic Alexandria the secrets of nature were indeed secrets, a sacred arcane mystery for the chosen few. in conse-quence many of the ancient scientific texts and collecti-ons of recipes which survived to the Middle Ages inclu-ded warnings against revealing the secrets within.

This knowledge of the properties, behaviour and transformation of materials became incorporated in Alexandrian intellectual life, combined with mystical theories about the nature of the material world and its relations with the spiritual world. This intellectu-al and theoretical interest of alchemy in craft proc-esses has the consequence that craft texts (useful for the artisan), and alchemic texts (useful for the philos-opher), treat the same processes and materials, and therefore theoretical alchemic texts may be mistaken for craft texts, with the consequent misunderstand-ings of actual workshop practices. As alchemic texts abounded in the Middle Ages, this potential confu-sion is highly relevant to the study of mediaeval artists’ recipe books.

Alchemic texts contain many recipes for producing colour changes. Hellenistic texts (notably the Stock-holm Papyrus and Leiden Papyrus X) are dominat-ed by recipes for alloying and dyeing. Many alchemi-cal recipes are concerned with the transformation of colour that indicate the progressive stages of the great “Work” of the alchemists, i.e. the manufacture of the philosophers’ stone. colour changes in materials indi-cated transformations of the material.

it is therefore now time to look at such a colour-change “alchemical” recipe, i.e. a recipe for a pigment “made by alchemy”:

Of Vermilion. If you wish to make vermilion, take a glass flask and spread the outside with clay38, and

37 The subject of the origins of experimental science, and its interre-

lationships with magic, is vast. The classic study is Thorndike, Lynn.

(1923–58): A History of Magic and Experimental Science (8 vols.

London: Macmillan & Co., and New York: Columbia University Press).

38 “luto” From this kind of application, this form of sealing a vessel was

commonly known as “philosophers lute”.

21

Fatto d’Archimia: alchemy and artifi cial pigments

so take one weight of quick silver, and two weights of sulphur, white or yellow in colour, and put that same fl ask on three or four stones, and put a fi re from char-coal all around the fl ask, but the fi re nevertheless very slow, and thus cover the fl ask with a very small tile, and, when you shall see smoke coming from the mouth of the fl ask that is blue, cover; and, when yellow smoke comes out, again cover; and, when you shall see red vermilion-like smoke come out, so remove from the fi re, and you have the best vermilion in the fl ask39.

cennini said that vermilion was “made by alchemy, prepared in a retort [i.e. a closed glass vessel]”, as this reci-pe describes. This is what we would today call a chemi-cal synthesis. Recipes for synthesis of vermilion from its components in this way are found in manuscripts at least as old as the eighth century (the Lucca MS).

now vermilion was very interesting for alchemists, and the relation of vermilion to theories of alchemy is one of the strongest reasons to be aware of mediaeval alchemical theories.

39 De coloribus et mixtionibus, my translation.

Alchemical theories of matter

To understand why the synthesis of vermilion was of such interest to theoretical alchemists, let us look at some alchemical theories. Alchemy had a variety of theories about matter. The mediaeval “Four-element” theory is well known. Probably originating in Hellenistic Alexan-dria, it remained current for a considerable period. All matter was made from the four elements (fi re, air, water, earth) mixed in various proportions.

To illustrate why there are so many recipes for synthet-ic vermilion, and how there is such a crossover between alchemic texts and books of colour recipes, it is useful to consider the alchemic processes for transmutation. in nature, the four elements were in a state of fl ux. in some circumstances the elements could change into one anoth-er. So if all materials were composed of the four elements, the only differences being due to the proportions of each element present, then this meant transmutation was possible, and occurred naturally, as the proportions of the elements varied in a substance. Transmutation was an observable fact, as ice melts to water, as wood turns into fi re, smoke and ash, or as food turns into fl esh.

There was another complementary theory for the nature of metals. An alchemist would see these vermil-ion recipes as also revealing the mystical preparation of “metals” (especially gold) by means of the from the alchemical “sulphur-mercury” theory. This held that all metals were made of sulphur and mercury. Transmuta-tion of base metals into gold rested on the belief that base metals were impure or unripe gold40. All metals were thought to be in essence the same. Metals were composed of the four elements, but also of two “exhalations” of the earth: “earthy” smoke (responsible for mineral properties) and “watery” vapour (for metallic ones). These exhalations were proposed by alchemists to be, in varying propor-tions, the constituents of all metals41, and to correspond to a sort of “ideal” or “philosophical” sulphur and mercu-ry. They realised that these “ideal” materials did not corre-spond to the ordinary sulphur and mercury42 (which, it was known, combined to give vermilion). But neverthe-less, in theory, any metal could be transmuted into any

40 A theory of Aristotle, developed and fi rst clearly stated by the Arab

Geber (Jabir ibn Hayyan) in the eighth century.

41 “Metals are all, in essence, composed of mercury combined and soli-

difi ed with sulphur”, Geber, “The Book of Explanation” [“Kitab al-Idah”].

42 “Not vulgar and such as are sold by the Merchants and Apothecaries”,

as Nicholas Flamel said.

Figure 1. De natura rerum by Isidore of Seville (560-636), printed at Augsburg

in 1472. The diagram shows the interrelation of the four elements with their

two pairs of opposing qualities: hot and cold, moist and dry. The elements are

related to the macrocosm (mundus), specifi cally to the seasons of the year

(annus), and to Man and his four humours (homo).

22

Fatto d’Archimia

other. Various experimenters, and numerous surviv-ing written recipes, claimed to produce gold. Metal was thought to be gold when its colour was gold, but it is debatable to what extent it was always believed that a gold metal was in fact gold. The distinction between making counterfeit gold and making real gold by transmuting base metals depends on your scientific paradigm as to wheth-er you believe transmutation is possible, and whether you think that you are actually making true gold, or whether you know it is false but are deliberately falsifying.

it is important for us to be aware of this theory, as a colossal number of recipes combining “sulphur” and “mercury” (which today we assume are apparently for making the pigment vermilion) are present in mediaeval texts. As cennini wrote: “it would be too tedious to set forth in my discussion all the methods and recipes”, and this is partly why.

The combination of sulphur and mercury as the parents of all metals was of scientific interest to the alchemists, as was the philosophically important cycle of native mercury ore (raw cinnabar) via mercury back to vermilion. not all such recipes, therefore, are to be taken as pigment recipes, but rather (i would suggest) some are to be taken as philosophical demonstrations: either the combining of “ideal” mercury and sulphur to produce the red philosopher’s stone, or (if carried out as a demonstration) to show that the mercury and sulphur we buy in the shops are not identical with their philosophic counterparts or, in the hands of a literal-minded experimenter, to try to find ideal proportions to make a metal, ideally gold. This is almost certainly why the recipes disagree so much as to relative quantities. The correct proportion of Hg:S, 200:32, is never found.

For all these reasons therefore –philosophic and alchemic interest in craft processes, the sequence of colour changes in transmutation, and changes in colour reflecting changes in material– texts that appear to be recipes for producing colours abound. Some of these subsequently found their way into the very mediaeval texts with which we are concerned for the history of mediaeval artists’ techniques and materials. Some of it however is truly symbolic, and reflected a theory we no longer support in any way. it is therefore important to be aware that some may have had purely alchemic origins.

Alchemy and its influence on artists’ practical texts

As we have seen, alchemy sought to explore and explain the secret workings of nature, and was driven

–and probably largely financed– by the desire to trans-mute base metals into gold and to prepare an elix-ir for prolonging life. As we have seen, simultaneous-ly with scientific and technical advances there was, in Alexandria in the third century Bc as there is today, a strong counter current of irrationalism and mysticism. These might be mixed in a single individual; for exam-ple, Hero of Alexandria invented “magical” devices for temples based on a good understanding of mechanics and hydraulics. it was in this mixed climate that alche-my originated. in addition to these two types of char-acter or personality –scientific and mystical– there was also the artisan, some knowledge of whose craft, as we have seen, had already become part of intellectu-al discourse. An important impetus for the develop-ment of theoretical alchemy seems to have been an attempt to explain technical processes such as dyeing, glasswork, and metallurgy, using theories derived from the Greek philosophers’ speculations, deductions and theoretical models of “the nature of things”.

Alchemy, medicine and artists’ pigments

A widespread and long-lasting model for the physical world and for medicine was the correspondence between the “Macrocosm” and the “Microcosm”. it was believed that the Macrocosm (or outer universe, i.e. the great systems of the cosmos, planets, winds, and elements) obeyed the same laws as the Microcosm (the body and soul of Man), and that furthermore a sympathetic influence existed between events in the Macrocosm and Microcosm. The best known example of this is astrology. Another well-known correspondence was between planets and metals.

The “doctrine of Signatures” expressed these correspondences in the form of visual clues to the hidden nature of nature: the appearance of a material, e.g. a plant or mineral, was a sign of its inner properties, or use. For example, lung-wort was held to look like a lung: it was telling us that it was to be used to treat lungs. These correspondences were often expressed in terms of allegorical symbols, either verbal, or diagrammatic. This is important for our purposes, as it is the verbal symbols that can make alchemic texts so unclear, and are indeed a convenient indicator of when a text is alchemic rather than practical in intent. Ritual words or incantations are not present in the body of true technical artists’ recipes, neither are “rationales” (explanations of the choice of materials, e.g. by the doctrine of signatures, as is common in medical texts).