Chapter 3Activity 6

PAINTS

Ancient paintings

Where did they get their paint from?

Ancient paint

• Ancient paints were derived from finely ground, naturally occurring minerals

Leonardo Da Vinci made some of his own oil paints

What ingredients are in paint?

• Pigment

• Binder

• Liquid/Solvent

Pigment

• finely ground particles or powders that are dispersed in paints, provide color

• produced as insoluble products of double replacement reactions

• May be a variety of colors depending on the metal ions that are involved in the compound

The mixture of cobalt(II) chloride and aluminum chloride is being

homogenized

Heating of the mixture in a test tube

After several minutes the reaction is completed

The finished productCobalt blue pigment

Pigments

Solutions of cadmium(II) nitrate and sodium sulfide

heating the solutions

precipitation reaction

Filtering the precipitateStirring the precipitate

Cadmium yellow pigment

Verdigris pigment[Cu(CH3COO2]2. Cu(OH)2. 5H2O

The reactions that produce an insoluble compound are called DOUBLE REPLACEMENT REACTIONS

Pigments

The reactions that produce an insoluble compound are called

DOUBLE REPLACEMENT REACTIONS   AgNO3(aq) + KCl(aq) ‑‑‑‑> AgCl(s) + KNO3(aq)

 

The product of this reaction that is insoluble in water is called the precipitate (ppt). It is this substance that can be used as the pigment in paints.

Pigments

NO3-precipitate

What ingredients are in paint?

• Pigment

• Binder

• Liquid/Solvent

Binder• A substance that is mixed with the pigment

to bind the pigment particles together• Once the paint is dry, it also binds the

pigment to the painted surface.• Could be

– oil (oil based paints)– acrylic resin (acrylic paints)– Egg yolk (tempera paints)– glue

• Egg Tempera

What ingredients are in paint?

• Pigment

• Binder

• Liquid/Solvent

Solvent• Usually a volatile liquid that is added to the

pigment and binder to adjust the viscosity (resistance to flow) of the paint.

• It evaporates and does not become part of the paint film that remains on the surface.

• Not all paints contain a solvent.

SolventThis is the paint when it is first applied: Pigment and binders are the circles and squares. The blue is the solvent.

The solvent is starting to evaporate. Pigment and binder come closer together.

Paint is dry, pigment and binder have been fused together and form a tough film.

Bill Nye House Paint

How oil Paint is made

How Latex Paint is made

• Smartboard review