Zinc dyes

Zinc white (zinc oxide)

Used since the mid-19th century. It is obtained by heating metallic zinc until it turns to steam. The zinc vapor combining with hot air forms zinc oxide in the form of a powder that settles in special vessels arranged. In the nearest one is a product contaminated with metallic zinc, the so-called "gold seal." The purity of the final product depends on the purity of the raw material. Pure zinc oxide is white with a bluish tint.
Zinc white, stored for a long time in a powdered state and exposed to air, absorbs water and charcoal from it, turning into zinc hydroxide. It crystallizes, loses its covering power and then needs a lot of oil.
Such a state can be removed by reheating.
Properties:

1.Weakly poisonous.
2.Insensitive to sulfur compounds.
3.Resistant to light.
4.Used in all techniques.
5.With permanent dyes gives permanent bonds.

Negatives:

1.Poor covering power.
2.Inflexible, prone to cracking.
3.Dries poorly in oil and delays drying of other dyes.
4.Gives gesso and paint layer brittleness.
5.Needs a lot of oil (20-30% oil per 100 parts of paint).
6.Sensitive to moisture and CO2.

Zinc white forms "zinc soap" with oil and becomes somewhat transparent over time.
Recognition:
When heated, it turns yellow and turns white when cooled. It dissolves in acids at ordinary temperatures, yielding a clear solution with no precipitate.

Zinc yellow (zinc chromate)

Yellowish-greenish color. It turns green on exposure to light. Sensitive to combinations with lead and zinc white, Neapolitan yellow, ultramarine and cobalt. It is partially soluble in water. It is primarily used in the production of so-called "zinc green" (Paris blue + zinc yellow).
Recognition:
Dissolves readily in hydrochloric and nitric acid to give a reddish-yellow solution.

Lithopone white (a mixture of zinc sulfide with barium sulfate).

Covers well in oil (but less well than lead white).
Not resistant to light (blackens).
In combinations with copper and lead, it also blackens. The better grades of lithopone, which do not contain chlorine impurities in their composition, are more resistant to light. It is not sensitive to sulfur connections. Quite flexible.