PIGMENTS

Chorme Yellow

Description.
Relatively inexpresive yellow pigment with high covering power but with only fair lighfastness and chemical stability. The Chrome colors were in use by 1816 but on a limited basis. Because the pigment tends to oxidize and darken on exposure to air over the time, and it contains lead, a toxic and heavy metal, it has been largely replaced by another pigment: Cadmium yellow.

Origin.
The name Chrome yellow comes from the name of a chemical element. It is derived from the Greek word "chrōma", meaning color, because many of its compounds are intensely colored.
It was discovered by Louis Nicolas Vauquelin in the mineral crocoite (lead chromate) in 1797. Crocoite was used as a pigment, and after the discovery that the mineral chromite also contains chromium this latter mineral was used to produce pigments as well.


Louis Nicolas Vauquelin

Translations
German: Chromgelb
French: jaune de chrôme
Italian: Giallo de cromo
Spanish: Amarillo Cromo, también llamado cromato, amarillo de plomo o más coloquialmente, amarillo tráfico.


Timeline
In 1809, when Vauquelin published his full investigation of the color chemistry of chromium in the now-prestigious Annales de chimie, chrome yellow was already on the artists' palette. It appears, for example, in Thomas Lawrence's Portrait of a Gentleman, painted in 1810.
Chrome yellow started to be used at 1816 and we continius using it nowadays.


 Sir Thomas Lawrence. Portrait of a Gentleman (1810)


ACRYLIC

Acrylic is an appealing medium because of its versatility. We can use it watered down or thickly. There are also several of different acrylic mediums that artists can add to the paint to alter the texture or other characteristics of the acrylic paint.





What is acrylic?
Acrylic paint consists of pigment suspended in a binder of acrylic polymer emulsion. Water is the vehicle for the acrylic polymer emulsion. Acrylics are sold in tubes or jars, and can be applied in a number of different ways, paintbrush, palette knife, fingers, etc., they can be used right from the tube, in most cases the paint is mixed on a palette first. 
You can make acrylic paints by mixing pure powdered pigment with a binder and solvent: 
Add water or a clear alcohol to a pile of pure ground pigment, and mix with spatula. Once the pigments are completely dispersed, add the binder, and mix with spatula. The result is an acrylic paint that is similar to manufactured acrylic paint.