Decorating Techniques

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ceramic arts dail y.org

three great pottery

decorating techniques

a guide to sgraffito, how to make and use terra sigillata, and creating and coloring highly textured surfaceswww.ceramicartsdaily.org | Copyright 2010, Ceramic Publications Company | Three Great Pottery Decorating Techniques | i

Three Great Pottery Decorating Techniques A guide to sgraffito, how to make and use terra sigillata, and creating and coloring highly textured surfacesDecorating your work before its fired provides you with a lot of creative opportunities. At the soft clay stage, you can stamp and texture your clay using many types and kinds of objects. When the clay is leather hard, you can coat your work with colored slips and carve away to create patterns. And when your clay is bone dry, you can apply terra sigillata and burnish the surface to a high sheen.

Scratching the Surface: A Step-by-Step Guide to Sgraffitoby Wayne BatesSgraffito comes from the Italian word graffito meaning to scratch, and Wayne Bates does more than scratch the surface with this informative tutorial on the tips and techniques of getting the best results. Using both cutting and scratching techniques, he demonstrates the finer points of line work, scraping large areas and cross-hatching. If youre into making your own glazes, hes provided 19 colorful engobes along with 5 recipes for various clear glazes you can try out.

Burnishing with Terra Sigillataby Sumi von DassowTerra sigillata means sealed earth and comes from the name of a type of Roman pottery mass-produced around the first century AD. But the Romans copied the Greek technique used in their famous black and red pottery for hundreds of years before that. Here is a complete guide to making and applying terra sigillata, recipes, and troubleshooting.

How to Make a Textured Platterby Annie ChrietzbergLana Wilson is the maven of textures and reveals her signature technique for creating a textured platter. In her step-by-step procedure youll see how she adds so much character to her pieces and how she brings the clay to life. She also includes her simple glazing technique along with her recipes.

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Scratching the SurfaceA Guide to Sgraffitoby Wayne Bates

he word sgraffito is derived from the Italian word graffito, a drawing or inscription made on a wall or other surface (graffito also gave us the word graffiti). Graffito is past participle of sgraffire, which means to scratch. So the word sgraffito basically means to scratch and create a graphic or an image. In ceramics, sgraffito is a technique of ornamentation in which a surface layer is incised to reveal a ground of contrasting color. I use sgraffito to get a clean line without masking or rulers, and I do more cutting than scraping. I use a handmade tool that is thin and cuts smoothly. I cut when the piece is stiff leather hard, which makes straight lines possible. If the piece is bone dry, the cut will be jagged and brittle. If the piece is too soft, the tool raises the edge of the cut and makes a higher ragged edge. If your clay has grog in it, or anything coarser than fine sand, you wont get a smooth cut. I use a rubber-tipped air tool and a soft cosmetic brush to blow or brush off the cuttings. The cut pieces are

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still moist enough to stick if you touch them to the surface, so they should be removed frequently. You can use a thin coat of wax resist to protect light-colored areas from dark cuttings. The wax resist will burn off in the bisque. Ball clays are used for engobes because they are the most plastic clays and shrink the most allowing more room in the recipe for non-plastic color, frit, modifiers and fillers. Frit is used to bind the coating to the surface and to increase the interface with the pot and the glaze. Wollastonite is used

Plates, 10 in. (25 cm) square, sgraffito decoration with clear glaze fired to cone 5.

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I use an automotive-detail-type spray gun to apply engobes and glazes. It has a smaller fan size than the full-size gun, has good volume, and is much faster than an airbrush. Its a high volume/low pressure (HVLP) gun and it produces less overspray. I use a large HLVP spray gun for the cover glazes because of its high volume.

CAUTIONOverspray is hazardous. The engobe spray contains silica, which can be harmful if inhaled. Wear a mask, and make sure your booth has an exhaust system.

to add calcium so the chrome-tin colors will work, and flint is used as a filler and stabilizer for colors that flux the mix. I mix the engobes thoroughly and screen them through an 80-mesh sieve. Most of my colors come from commercial glaze stains although not all commercial stains will work, but if you think of engobes as being closer to glazes than slips, additives can help produce the right colors. Changes in the frit affects how fluid an engobe is and how it works with the glaze. It can also produce a vitreous, glaze like surface. Changes in the amount of ball clay will make the engobe more or less plastic and change whether it goes on very wet pieces or bone-dry pieces. I use a matt and a shiny glaze to cover the engobes on the face of the pieces and these two glazes are what I call color friendly. To get as many colors as possible, they have to work with the chrome-tin

colors, i.e., the reds, pinks, and purples. The molecular recipe has to have three times more calcium than boron for these to work. They have that ratio and will produce the right color with all my engobes. I do use barium for what it does for the colors and for the matt. The potential problem with it has to do with the heavy metals and the possibility of leaching. From what I can find out, if a glaze has less than 15% barium in the percentage composition, it will not promote leaching. From the tests I have done, the glazes that I now use do not promote leaching when used over the engobes. I do use a liner glaze for liquid containers and I dont use the solid color glazes on eating surfaces. I spray very wet, as if Im pouring on a small stream of the glaze or engobe on the piece. The engobe sets quickly because the leather-hard piece can absorb some water, but too much engobe

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Place the platter on the wheel over a piece of foam and create the center spiral as the wheel turns.

Move the platter to a banding wheel and create freehand marks.

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Scrape off large areas last using the flat side of a rib.

Cross-hatching is done with a serrated tool.

and the piece can collapse. If the engobe is too thick, it makes the color and the glaze crawl. Set the fan for a tall oval and overlap the spray by 50% with the piece on a banding wheel turning smoothly through the spray. Practice spraying with paper plates so you can cover the plate smoothly with no bare spots or dusty areas. The four colors of this color set are black, french green, chartreuse, and crimson and are applied from dark to light (figures 12). The spray adds water to the piece and it must dry to the leather hard state before it can be carved. When

dry enough, store the pieces on cloth on top of plastic, and place cloth over them to prevent condensation from the plastic marring the color (figure 3). First I create the center spiral and circle using a foam rubber chuck on the wheel (figure 4). All the other lines are done freehand on a banding wheel (figure 5). The scraping of the larger white spaces is done last, when the piece is even harder. I try to take off only the layer of color (figure 6). I use the tool tip to make a sort of ditch that you can scrape to or from to make the larger white

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areas. I use the flat side of a rib to make the larger cuts. There will be some edges that can be felt, and glazes will break away from these edges, but the glaze will fill in to make it smoother than when cut. Small nicks and cuts can be patched, but the spray overlaps are very hard to color match, so it is best to avoid mistakes! When almost bone dry, use 0000-grade steel wool to lightly

smooth some of the cuts and to remove small bits of color. Cross-hatching is another way of exposing the white of the porcelain and is done with a serrated-edge tool (figure 7). I add black dots of engobe using a squeeze bottle. When all the carving is done, the piece is air-dried then bisque fired, then a clear satin matt or a shiny glaze is sprayed on the front and solid color glazes on the back.

ToolsMy sgraffito tool tips are made from the main spring of a pocket watch. The spring metal is thin and strong, doesnt have to be sharpened and keeps the same feel as it wears away. To make the tip, cut a piece of spring, heat it with a small torch and bend it to the shape you want. A small rounded point is used for the line cutting tips, and a broader rounder tip for large cuts. Glue the tip with Elmers glue into the brass ferrule of the trimming tool and allow it to harden. Lightly heating the ferrule softens the glue and the ferrule can be removed and another tip glued into the tool. For ribs, cut them with tin snips from sheets of metal and flatten the edges, making two square edges for scraping (do not sharpen the edges). You can also cut serrated-edge ribs with the snips.Assorted and modified tools used in sgraffito. Detail of trimming tool with ferrule removed and watch-spring cutter formed to desired contour.

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RecipesSgraffito techniques can be a lot of fun, especially with a large color palette of engobes. Most of my colors come from commercial glaze stains. Frits, fillers, and retardants are added, depending on the colorant used. The following engobes are mixed with Mason stains.

UBR-17 Seal BrownC&C Clay..................... 40 % Nepheline Syenite............... 20 Wollastonite.................... 10 Seal Brown #6153............... 30 100 %

UGR-10 Silver GrayC&C Clay..................... 60 % Ferro Frit 3134.................. 10 Silica......................... 10 Silver #6530.................... 20 100 %

EngobesUBL-45 BlackC&C Clay..................... 50 % Ferro Frit 3195................. 20 Black #6600.................... 30 100 %

UB-18 Teal BlueC&C Clay..................... 60 % Ferro Frit 3134.................. 30 Teal #6305..................... 10 100 %

UPR-32 Deep OrchidC&C Clay..................... 50 % Nepheline Syenite............... 10 Deep Orchid #6303.............. 30 Wollastonite.................... 10 100 %

UR-28 Dot RedC&C Clay..................... 50 % Wollastonite.................... 20 Ferro Frit 3134.................. 10 Crimson #6006................. 20 100 %

UR-31 CrimsonC&C Clay..................... 50 % Ferro Frit 3134................. 20 Wollastonite.................... 10 Crimson #6006................. 20 100 %

UY-38 Hot YellowC&C Clay..................... 50 % Nepheline Syenite............... 10 Ferro Frit 3134.................. 10 Wollastonite.................... 10 Yellow #6481................... 20 100 %

UBL-46 Blue BlackC&C Clay..................... 50 % Nepheline Syenite............... 10 Silica......................... 10 Black #6616.................... 30 100 %

UG-35 French GreenC&C Clay..................... 50 % Ferro Frit 3134................. 15 Wollastonite.................... 10 French Green #621.............. 25 100 %

UW-1 WhiteC&C Clay..................... 30 % Nepheline Syenite............... 20 Ferro Frit 3134.................. 10 Wollastonite.................... 10 White #6700................... 30 100 %

UB 22-Turquoise BlueC&C Clay..................... 50 % Ferro Frit 3134.................. 10 Wollastonite.................... 10 Zircopax....................... 10 Turquoise #6390................ 20 100 %

UG-41 ChartreuseC&C Clay..................... 50 % Ferro Frit 3134.................. 20 Chartreuse #6236............... 30 100 %

UB-7 Peacock BlueC&C Clay..................... 40 % Nepheline Syenite............... 10 Peacock Blue #6396.............. 40 Wollastonite.................... 10 100 %

UBL-41 Light Blue BlackC&C Clay*..................... 60 % Nepheline Syenite............... 10 Wollastonite.................... 10 Silica......................... 10 Black #6616.................... 10 100 %

UP-49 Hot PinkC&C Clay..................... 40 % Ferro Frit 3134................. 40 Pink #6020.................... 20 100 %

UPR-31 Pansy PurpleC&C Clay..................... 50 % Nepheline Syenite............... 10 Wollastonite.................... 13 Pansy Purple #6385.............. 27 100 % *C&C clay is a ball clay . If not available, another ball clay may be used, but the results may vary . Although formulated for cone 6, many of these will work at higher and lower temperatures . Always test new recipes before using .

UP-34 CoralC&C Clay..................... 50 % Ferro Frit 3134................. 10 Wollastonite.................... 10 Coral #6090.................... 30 100 %

UG -69 Turquoise GreenC&C Clay...................... 50 % Wollastonite.................... 10 Ferro Frit 3134.................. 20 Turquoise #6393................ 20 100 %

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RecipesGlazesThe following glaze recipes can be used over the engobes, but they can also be tinted with stains.

R-1030 Satin Matt*Cone 5Barium Carbonate............... 11 % Wollastonite.................... 15 Ferro Frit 3134.................. 19 Nepheline Syenite............... 33 EPK Kaolin.................... 16 Silica.......................... 6 100 % Similar to R-1015 but lower temperature . Will go shiny if fired higher . Top of my kiln .

G-19 Shiny ClearCone 6Wollastonite.................... 30 % Ferro Frit 3195.................. 30 EPK Kaolin..................... 20 Silica......................... 20 100 % Color friendly base, will produce shiny versions of most of the Mason stain colors . Can be used as a liner glaze, unlikely to produce leaching .

R-1012 Satin Matt*Cone 5Barium Carbonate............... 11 % Whiting....................... 12 Ferro Frit 3134.................. 17 Nepheline Syenite............... 44 EPK Kaolin...................... 7 Silica.......................... 9 100 % Similar to R-1015 but lower temperature . Middle of my kiln .

Frosty MattCone 6Barium Carbonate............... 22 % Lithium Carbonate................ 5 Nepheline Syenite............... 60 EPK Kaolin...................... 8 Silica.......................... 5 100 %

High alkaline, distinct color characteristics, crystalline sugar like surface, turns copper turquoise, brightens most colors.*Contains barium . Can produce leaching when used with heavy metals . No claims made for success or safety .

R-1015 Satin Matt*Cone 6Barium Carbonate............... 16 % Wollastonite.................... 15 Ferro Frit 3134.................. 13 Nepheline Syenite............... 33 EPK Kaolin..................... 14 Silica.......................... 9 100 %

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Burnishing with Terra Sigillataby Sumi von DassowPhoto by ImageInation.

ome potters think of terra sigillata as the easy way to burnish. Terra sigillata is relatively quick and easy to apply, but there are various potential disadvantages compared to stone polishing: it can crack or peel off after firing; it may be difficult to apply an absolutely smooth coat without brush marks or drips; it will reveal all texture on the surface it is being applied to, for good or ill; and it will never quite yield the mirror-like shine you can achieve by burnishing with a stone. Which method of burnishing you choose will depend on the clay you are using, the way you are firing and your level of patience. The form you are trying to burnish may also dictate which method you can use a smooth surface with no folds or creases, and no impressed, incised or sculpted details is ideal for burnishing with a stone. If your form has a textured surface, or corners and curves which a stone cannot get into, then you probably need to use terra sigillata.

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Struck by Ricky Maldonado. 15 in. (38 cm) in height. Lowfire terra cotta clay, coil built, sanded using three grades of sanding sponges, coated with six layers of terra sigillata then burnished with hands using the oil from my body (I rub behind my neck or legs). Finished with dry-cleaner plastic wrapped around my fingers. Design drawn in black slip, then dots applied using low-fire glaze between the lines. Fired to cone 06.

The term terra sigillata, which means sealed earth, comes from the name of a type of Roman pottery massproduced around the first century AD. This pottery was decorated with impressed or stamped decoration, which is what the word sigillata refers to. (Think of the kind of stamp, or seal, which would have been used to seal wax on a paper document.) These pots were coated with the same kind of very fine slip which Greek potters had been using for hundreds of years to create their famous black and red pottery. Though many books incorrectly refer to

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Step 1: Weigh out Darvan 7 or 811 and add it to the measured amount of water. Helpful hint: If you always mix your terra sigillata in the same container, place a permanent water-line on the side of the container so you dont have to measure the water every time.

Step 2: Weigh out the dry clay, add it to the water solution, and mix thoroughly.

Stripes become noticeable down the sides of the container as the heavier particles begin to settle.

After settling (in this case, approximately 3 hours, but could be as long as several days), siphon off the middle layer of liquid from above the layer of sludge. Be careful not to get any of the settled sludge in your siphon.

this slip as a glaze, it was not actually a glaze but the material we now call terra sigillata.

Making terra sigillata

Terra sigillata, or terra sig for short, is made by mixing a suitable clay with water and a deflocculant and leaving it to stand until the heavier particles of clay settle out. (Deflocculant weakens the electrical attraction between particles of clay, thus breaking up small clumps of clay and allowing the individual particles to float freely.) The deflocculant causes the finer particles to float in the water, which can then be decanted for use. In general it is not possible to buy terra sigillata, so if you want to use it, you must make your own. To make terra sigillata, you will need a clear glass or plastic jar with a wide mouth, an accurate gram scale and a length of clear plastic tubing for siphoning. The only ingredients are water, dry clay and deflocculant. Many kinds and colors of clay can be used, including ball clay, kaolin, local clay or scraps of whatever clay body you usually work with. There are also many possible deflocculants, the most commonly used being sodium silicate, soda ash, Darvan 7 and Darvan 811. You might find recipes calling for Calgon water softener, but dont try those unfortunately Calgon doesnt work since it was reformulated to eliminate phosphates. Lye can also be used as a deflocculant, and I have even experimented with using the waste water from washing wood ash.

Not all clays are equally suitable to make terra sig, and the proportions of water to clay to deflocculant will be different depending on what clay you use. It is a question of experimenting with different types until you find something suitable. You can try substituting any dry clay, including scraps from your clay body, for the clays called for in the recipes which follow. The process is simple, but a bit time-consuming. First, measure your water, and stir in the deflocculant. Weigh out your clay and add it to the water. For best results, be sure to weigh these materials precisely. If you have a ball mill, you can ball mill the mixture, otherwise, shake or stir it vigorously. Then place the jar, loosely covered, somewhere where it wont be disturbed for several hours to several days, depending on the recipe. After the appropriate settling period, you will see a layer of dark sludge on the bottom of your jar, and if it has been a long settling period you may see clear (or possibly dark-colored) water on the top (this varies depending on the type of clay and length of settling). Its the part in the middle hopefully, about half the mixture which you need. Use a syringe to remove carefully as much of the water from the top as you can without taking any of the fine clay particles along. When clay starts getting into your syringe, its time to siphon off the middle layer into a clean container, using the clear plastic tubing or for a small batch, simply use the syringe. Dont be greedy. If you get some of the heavy sludge into your terra sig,

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Center a pot on the wheel upside-down, and while the wheel spins begin brushing on the terra sigillata from the foot. Apply two or three coats, until you cannot see the underlying clay color clearly.

Once you have applied enough terra sigillata to the lower portion of the pot, and it has soaked in so it is not glossy wet, use your fingertips to begin polishing the surface as you continue coating the pot with the other hand.

Turn the pot right-side up and finish coating it with terra sigillata. Apply just inside the lip; there is no need to coat the entire inside of the pot.

Using the polishing material of your choice-a carpolishing mitt works well -bring the entire surface to a high sheen.

it may never settle back out and youll have gritty terra sigillata which wont shine up as well. Its a good idea when you get close to the layer of sludge to switch to a new container, so if some of the sludge gets in you dont contaminate the whole batch. You now have a batch of rather thin terra sigillata (along with a lot of sludge which can be discarded or used for some other purpose). It can be used as is, or allowed to settle and evaporate for a few days before using.

Applying terra sigillata

Terra sigillata can be applied in two ways, by brushing or spraying. Brushing is easier, but may leave noticeable brush-marks. On the other hand, spraying requires more equipment, and may leave a bit of a pebbly texture where the droplets land on the pot. Before you apply terra sigillata, your pot must be smooth and dust-free. Terra sigillata is so fine that even if you cover a textured surface with several coats, the texture still shows. This is wonderful if you have a deliberately textured surface, and in fact, the only way to burnish a textured surface is with terra sig. However, if you have sanded the pot, the surface is likely to be covered with little scratches from the sandpaper, which will not be covered up by the terra sig. Even more important, if you have sanded your pot, you must carefully sponge off any dust. Dust will cause the terra sigillata to peel off after firing. Therefore, if you want to achieve a really smooth burnished surface using terra sig, it is most effective to apply it to a wheel-thrown pot which has been ribbed smooth after throwing or trimming, or if handbuilding, to smooth the entire surface at leather-hard stage with a rib.

Terra sigillata should be applied to a bone-dry or almost bone-dry pot. If you are brushing it on, you need to apply at least three coats. If you are putting white terra sigillata on white clay, three coats is probably plenty. The terra sigillata needs to soak into the clay, but should not be allowed to dry completely between coats. Once you have applied several coats, the surface should be buffed with your fingers, a cloth or chamois-leather before it dries completely. The pot is ready to buff when the surface looks waxy and grey but is no longer wet-looking. If it has lightened in color, it has dried too much and another coat of terra sigillata must be applied. For the greatest degree of sheen, apply three thin coats and buff after each coat. Watch out for two things when you are brushing on terra sigillata: dont let it drip down your pot, because the drips will show; and dont allow your brush to lose hairs, as the hairs will make a permanent mark. Be sure to use a good quality soft brush a watercolor mop brush works well. If you are brushing terra sigillata onto a wheel-thrown pot, the simplest way to apply a nice even coat is to put the pot on the wheel and let the wheel do the work for you while you move the brush up and down. Once you have enough coats on part of the pot, you can start burnishing with the fingertips of one hand while you are still brushing the terra sigillata onto another part of the pot with the other hand. If you have a large pot you are almost required to do this to get a really good polish, or the terra sigillata may dry out too much before you finish brushing it on. Dont touch the surface until it has soaked in, though if the terra sigillata comes off on your fingers, it isnt

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RecipesWhite Terra Sigillata3 .7 pints (2 .1 kg) water 2 .2 lb (1 kg) OM4 Ball Clay 25 g Darvan 7 or Darvan 811 liquid into a large clear container, discarding the sludge on the bottom of the original container . Let it settle for another 20 hours, then siphon the thin liquid from above the layer of sludge . As soon as you notice the liquid getting a little thicker, stop siphoning and discard the rest of the liquid along with the sludge .

Red Terra Sigillata3 .9 pints (2 .2 kg) water 2 .2 lb (1 kg) Newman Red Clay 30 g Darvan 7 or 811 Measure water into a large glass or clear plastic jar with a wide mouth . Add Darvan and stir. Add clay and shake vigorously . Leave undisturbed to settle for three hours . You will see a dark layer of sludge at the bottom of the container . Siphon off the liquid portion above the layer of sludge . Be careful you dont pick up any of the sludge . Discard the bottom layer of sludge . Try the terra sigillata on a dry test tile. If it doesnt give an adequate shine or still feels gritty when you rub it with your fingers, let it sit for another 1224 hours, siphon again and discard the new sludge . One sign that you have a bad batch of terra sigillata is if it soaks in and dries very quickly . If there are dark specks in the terra sigillata, put it through a 200-mesh sieve . Even if there arent dark specks it wont hurt to screen it anyway . It should be about the right consistency to use right away (a specific gravity of 1 .15) but if you want it thicker, let it evaporate for a day or two . Apply two or three coats to bone-dry ware, allow to dry just until the surface isnt wet, and burnish with fingers, a soft cloth, nylon stocking, chamois-leather, car-polishing mitt or a plastic bag . Dont touch the wet surface and make sure your polishing cloth is very clean . For the greatest shine, apply three thin coats, polishing between coats . For colors, add oxides or stains after settling. If you add too much, the terra sigillata wont burnish as well because these materials have a larger particle size than terra sigillata .

Jan Lees recipesBall Clay Terra Sigillata28 lb or 3 gallons (16 liters) water 14 lb (6 .35 kg) Ball Clay 3 tablespoons Sodium Silicate Let settle 48 hours before decanting.

Orange Terra Sigillata14 lb (6 .35 kg) Dry Clay (Orangestone from Highwater Clays) 28 lb or 3 gallons (16 liters) water 3 tablespoons Sodium Silicate Let settle 6-7 hours before decanting. Allow to evaporate to a specific gravity of 1 .15 . Jan Lee also sometimes adds crocus martis (a form of iron oxide) to white terra sigillata to make a purplish color . She uses teaspoon per cup of terra sigillata .

Charles and Linda Riggs Recipe28 lb or 3 gallons (16 liters) water 15 lb (6 .8 kg) XX Saggar Clay or OM4 Ball Clay 1 tablespoons Sodium Silicate 1 tablespoons Soda Ash Place the water in a 5 gallon pail and add soda ash and sodium silicate . Stir in clayif you have a hydrometer, only add enough clay to get a specific gravity of 1 .15 . Let it settle for 10 minutes then pour off the

Some of these recipes suggest checking specific gravity with a hydrometer. You can also pour 3 fl oz (100 ml) of terra sigillata into a graduated cylinder and weigh it if it weighs 115 grams it has a specific gravity of 1.15. This is the recommended consistency for terra sigillata. If it is much thinner it is hard to apply enough without over-saturating your pot with water. If it is much thicker, it may peel off after firing. In practice you will get to know just how you like your terra sigillata and you wont have to check the specific gravity of every batch you make. For more information about making terra sigillata, especially if you want to try clays other than those called for in these recipes, I would highly recommend consulting a comprehensive book from the European Ceramic Work Centre called The Ceramic Process: A Manual and Source of Inspiration for Ceramic Art and Design.

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Saggar-fired Orb by Charles and Linda Riggs, 2003. 9 in. (23 cm) in width. White stoneware sprayed with white terra sigillata, polished with a soft cloth, bisque fired to cone 010, saggar-fired in a raku kiln with wood shavings, steel wool, copper, and salt.

Naked Raku Orb by Charles and Linda Riggs, 2003. 7 in. (18 cm) in width. Stoneware painted with white terra sigillata and polished with a soft cloth, bisque fired to cone 010, covered in resist slip and glaze. Sgraffito through glaze before raku firing to 1400F (760C).

ready to burnish yet, and you will mar the surface by touching it. After you have applied enough terra sigillata to the whole pot, and there are no wet patches, then you can start using a chamois-leather or a soft cloth, or even a thin plastic shopping bag, to bring the surface to a high gloss. If you are applying terra sigillata to a handbuilt or sculptural piece, you may find it impossible to use the wheel to help with the job. In that case, you can still brush it on, but be careful not to touch any wet spots. You may also want to experiment with pouring, or even dipping if you have a large enough batch of terra sigillata and a way to safely hold a delicate piece of greenware.

Troubleshooting

Terra sigillata occasionally suffers from problems adhering to the clay it is applied to. Terra sigillata is not integral to the material the pot is made from, as is the surface of a stone-burnished pot; at the same time it doesnt adhere by melting like a glaze does. Some potters prefer to burnish with a stone for this reason, but you can keep this problem under control by attention to some rules of thumb in applying terra sigillata and firing your ware. Most important

is to make sure the terra sigillata is quite thin and watery. It should take several coats to cover your pot, and the final depth of applied terra sigillata should be a fraction of a millimeter. The pot must be dry but not dusty. If necessary, use a damp sponge to remove dust from the surface before applying terra sigillata. However, beware of sponging the surface of your pot too much: every time you rub it with a wet sponge you are removing particles of plastic clay and leaving behind the heavier particles of clay and coarse grog, which dont hold on to terra sigillata as well. After coating your pot, allow it to dry completely before firing; it is a good idea to wait 24 hours. Avoid a too-rapid increase in temperature during any firing a pot which comes out of a bisque firing perfectly smooth may peel in a hot and fast pit-firing. If you experience a great deal of peeling despite following all these rules, you may have to change the clay you use or the terra sigillata recipe. One last thing to try is adding a little CMC gum to your terra sigillata. This is a gum which is often used as a binder. It comes as a powder which has to be dissolved in hot water before it can be added to your terra sigillata. Add only a very small amount at a time and test as you go. CMC may reduce the level of sheen

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Eagle Vase by Sumi von Dassow, 2008. 9 in. (23 cm) in height. Coil built from red stoneware (Navajo Wheel Clay from Industrial Minerals Co.), burnished with a stone, decoration with terra sigillata, and smokefired. Photo by Sumi von Dassow.

you get from your terra sigillata, and it will slow the drying time. Many potters use terra sigillata as a canvas for the fire to paint on, either pit firing or saggar firing their burnished pots. However, other potters like the satiny surface of terra sigillata as is, without any special firing. Ricky Maldonado is a potter who uses terra sigillata as a base for painting intricate patterns, rendering them with tiny dots of low-fire glaze covering the burnished surface of his pots. You can also try using terra sigillata to partially cover a surface which has been burnished with a stone. In this

way you can have a multi-colored burnished pot with a high level of sheen. I frequently use terra sigillata made from Cedar Heights Redart clay to paint intricate patterns of fine lines on burnished pots made from red clay. I then smoke-fire these pots to achieve a black-on-black effect. I adopted this process because I found that plain clay slip often rubs off a burnished surface, while the process of buffing terra sigillata to shine it up seats it even on an already burnished surface.

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Lana Wilsons

Textured Platterby Annie Chrietzberg

Detail of one of Lana Wilsons richly textured platters.

L

ana Wilsons career spans more than 40 years and includes a vast repertoire of pieces and surface considerations, which she regularly shares with students. She teaches, on average, a workshop a month, and loves to do so. Its so easy, really. The people are always interesting; you are instantly submerged in a milieu of like-minded people. I love the humor, and people are so kind. What Lana really appreciates about teaching workshops is how much diverse experience there is in the audience. At any given time, your audience might include

a nurse, a kiln builder or a cook, and when people open up about those things, I learn so much, she said. And, if I come across something in ceramics that I dont know about, Ill ask the audience, and more times than not, Ill learn the answer. Lana worked with functional stoneware for the first seventeen years of her life in ceramics. And then, a job at a community college caught her eye, so, at age 43, she went back to school to get her masters degree. For Lana, graduate school completely changed the course of her work. Number one, it opened up the way to lots of ex-

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1Smooth out a slab, layer, and press in objects then texture the surface.

2Use hand tools, stamps, and found objects to embellish the slab.

3Roll over the texture with a rolling pin, to soften and tuck in the marks.

4Use a handmade viewfinder to select an interesting area.

5Cut out a dart then use it as a pattern to cut the remaining darts.

6Lift and connect the edges where the darts have been removed.

ploring and experimenting, which has never ended, she said. Number two, I started making non-functional work and using the electric kiln exclusively, neither of which Id ever done before. Now, Lanas focus has returned to functional pieces. She told me one reason: I want my grandchildren to eat off of things that I have made.

Texture Throughout

Lana applies texture in layers, and does so throughout her making process. During my visit, she made a serving platter to demonstrate how she works. After using a slab roller to make a large slab, she lays out some fruit netting on the table, and sets

the slab on top of it. This netting forms the basis of the texture composition on the back of the piece, though Lana will embellish it more at later stages. After smoothing the front of the slab with a small squeegee, Lana uses a wooden rolling pin from a pastry store to lay down some waffle texture, which created impressed squares, then in an adjacent area, she lay down and rolled over plastic sink mats that left larger, high-relief squares (figure 1). I watched her then target and go after some of the high relief squares with her small hand-held stamps, and some found objects, inverting them with embellishment (figure 2).

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7Prop the piece up, level the sides, and adjust as needed.

8For handles, shape cones from large triangles cut from a textured slab.

9Lift and drop the cone two or three times to get an organic shape.

10Slip and score the handle in place, then support it with foam.

11Turn piece over on foam supports, fill seams and adorn the repair.

12Make a foot from a long, thin piece cut from a textured slab.

I was surprised when she picked up her rolling pin and rolled over the work she had just done (figure 3), but she explained to me, You see, this softens it and makes it more interesting. I dont want it to look like plastic surgery. I dont like the whole Southern California glitzy sequin scene, I like old, worn friends. I like layers; I walk regularly in the Torrey Pines State Reserve when Im home in San Diego. I love those layers of information around me. I looked, and the effect she had created by rolling over existing texture was to tuck in all the little marks she had made, like treasures in lockets. After tucking in her

preliminary and secondary texture with a rolling pin, Lana embellished further with one of her new favorite items, the red scrubby applicator from a Shout bottle, and an old favorite, a seamstress marking tool.

Forming the Platter

Lana had created a slab much larger than what she actually needed for the piece she had in mind. She cut a framing device out of a piece of paper roughly the proportions of her intended serving dish (figure 4). She used this viewfinder to locate the best part of her texture drawing, marked the boundaries by laying down a straight edge then, using

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Smooth the foot with a roller and cut decorative arches through it.

Use a pony roller to bevel and finish both sides of the platters edge.

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the straight edge again, cut out the shape. Lana needed to take two darts out of each end to have the flat shape rise up into the form she wanted. Oh, I suppose I should use a template, but I never do, she quipped, knowing that I am a template fiend. I can never find the one I need when I need it, besides, I know what shape I need to cut out, and after I cut the first one, Ill use it to cut the other three, she explained, as she cut out and removed the first dart. She took the triangular piece of clay she removed, turned it over, and set it gently down to trace it where she wanted the second dart. She then took those two cut-out and placed them on the other end, and traced and cut out the remaining two darts (figure 5). The size of the dart determines the shape of the final form. After slipping and scoring, she simply lifted and butted the joining edges together (figure 6), and then used small pieces of foam to prop up the ends

of the serving dish which allows them to firm up while supported. She fills in gaps in the texture where the darts were removed with paper clay to prevent cracks from forming along the seam. To address the sides, Lana grabbed a couple of paint stirring sticks, which she used to lift the sides and then shoved pieces of foam beneath to hold them in place. She filled in gaps that had been made by cutting through existing texture on the edges, and then compressed and beveled those edges with a pony roller. Then, she used a spirit level to make sure the edges, were, um, level (figure 7). I dont know a gallery who would take a piece thats not level, she murmured as she made slight adjustments. There we go!

Making HandlesThe next task was to make the handles. First, she textures a slab and cuts out large triangles, then she rolls them into a cone (figure 8), seals them using a pony roller,

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and drops them on her workbench (figure 9). They magically gain character with each whump. Once she is satisfied with the result, she cuts away excess clay with a fettling knife, scores and slips the end of the serving dish, as well as the inside of a handle, and then attaches it, stacking foam beneath it for support (figure 10). Lana constantly manipulates the surface of her pieces as she is making, adding texture as she goes. After attaching the handles, she grabbed a wooden dowel with sharpened ends (a pencil would work, too) to both re-draw and enhance existing lines. After the piece had dried to leather hard, she removed the bolsters and turned it over on a large piece of foam to access the bottom. She filled the gaps in the seams with paper clay, again to strengthen them and prevent cracking (figure 11). When she makes a repair like this, she adorns it. I could teach a whole course on cheating, she joked, while rolling a seamstress marking tool over the filled-in seam.

Adding a FootThe last part of the serving dish project was to make and attach a foot. Before she had turned the piece over, she had taken an approximate measurement with a seamstress measuring tape, and had created a long slab to texture. She played around a bit with some scrap clay to determine

the appropriate height, textured the slab, and used a straight edge to cut a long strip of clay for the foot. She picked up the long strip in loose folds and dropped it a few times on the table. This makes an undulating line I just love, she told me as she worked. She placed the foot on the bottom of the pot, shaped it how she wanted it, and cut the excess away, then joined the foot into a ring. After scoring and slipping the areas that need to be joined, she attached the foot ring to the bottom of the serving dish and used a dry soft brush to remove excess slip and blend the seam (figure 12). She then used a common loop tool to create a little looped arch on each side of the foot (figure 13). She rolled the edge with a pony roller, used a ware board to flip the piece right side up, and used the spirit level again to make adjustments (figure 14). Lana has a delightfully free, direct, and easy way of making, but dont let that fool you into thinking she doesnt take her time in the studio seriously. Ive changed my style of work about six times through out my career., and each time it takes me about six months to a year to figure it out, she told me. People dont realize that being an artist is really about daily discipline; when Im working, I want my time to work. Im not one of those ladies who does lunch. Ceramics is far too expansive for that.

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FinishingLana Wilsons work is mostly black and white with bits of vibrant color splashed about. She says, I have a background in painting, and this technique really appeals to the painter in me. She gleaned this current surface treatment from two artists, Denise Smith of Ann Arbor, Michigan, and Claudia Reese, a potter from Texas. cone 5, though she fires it to cone 6. This clay body is half porcelain and half white stoneware. Its not as white as porcelain, but it does fire white rather than yellow in oxidation, isnt as finicky as porcelain, and works well with Lanas making methods. If youre buying clay from the East Coast, she suggests a clay body called Little Loafers from Highwater Clays.

CAUTIONYou must wear a respirator during this stage. In the final step, she dips the piece in a clear glaze, and fires to cone 6. Through lots of experimenting, and with lots more to go, Lana finds that ending with a dark color on top works best for her.

Simple SlipTo prepare the slip, Lana takes 100 grams of small pieces of bone dry clay and adds 1050 grams of a stain. The percentages of stains varies according to the intensity of color she is trying to achieve. The clay Lana uses is Half & Half from Laguna, formulated for firing at

Easy ApplicationThe technique is simple. On a piece of bisqueware, first brush on black slip or one of the base colors (figure 1) then sponge it off, leaving slip in the crevices (figure 2). Then, using colored slips dab on bits of color here and there (figure 3). Remove some

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NOTEStain or oxide-bearing slips applied to surfaces that come into contact with food need to be covered with a food-safe clear glaze.

of that with steel wool (figure 4). I cant use water for this step or it will muddy the colors, Lana explains.

RecipesBase Coat or Wash Colors6600 Best Black................. 10 % 6339 Royal Blue............... 5-10 % 6069 Dark Coral................ 35 %

RecipesThere are two groups of colored slips. The first group Lana uses for the base coat that she washes off, leaving color in all the recesses. The accent slips are more intense and removed with steel wool. All stains are Mason stains except for 27496 Persimmon Red, which is from Cerdec. Add the stains and bone dry clay to water and allow to sit for 3060 minutes so it will mix easier.

Accent Slips6129 Golden Ambrosia........... 6485 Titanium Yellow............ 6024 Orange................... 6236 Chartreuse................ 6027 Tangerine................. 6211 Pea Green................. 6288 Turquoise................. 6242 Bermuda.................. 6069 Dark Coral................ 6122 Cedar.................... 6304 Violet.................... K5997 Cherry Red*.............. 27496 Persimmon Red (Cerdec)*.... * inclusion pigments 30 % 20 % 30 % 50 % 15 % 50 % 50 % 10 % 35 % 25 % 60 % 30 % 30 %

Kate the Younger Clear GlazeCone 6Ferro Frit 3195.................. 70 % EPK Kaolin...................... 8 Wollastonite.................... 10 Silica......................... 12 100 % Add: Bentonite................ 2%

From Richard Burkett . Use over colored slips . Shiny, resistant to crazing, cool slowly .

Texture and isolated areas of bright color make Lana Wilsons work really pop.

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