Zinc white
The first non-toxic white, and the coldest. Zinc white gave nineteenth-century painters a way to lighten a colour without warming it, and it is now the pigment conservators worry about most, because a great deal of the painting made with it is quietly falling apart.
Origin
Zinc oxide had been known as philosopher's wool, a white fluff condensed from burning zinc, long before anyone made paint from it. It was proposed as an artists' colour in the 1780s and offered commercially by Winsor & Newton from 1834 under the name Chinese white, initially as a watercolour, where it solved a real problem: lead white blackens in watercolour and zinc does not. Industrial production expanded through the century as a house-paint alternative to lead, driven by the growing evidence that lead white was poisoning the people who applied it.
In art history
The Impressionists took it up because it is a cold, neutral, greenish white that does not push a mixture towards yellow the way lead white does — useful when the entire project is the accurate rendering of daylight. It is common in Monet, Van Gogh, Seurat and in most painting after about 1850, usually alongside lead white rather than replacing it. Zinc appears in nine eras here, all of them modern. Its later history is unhappy: paintings from the late nineteenth and twentieth centuries containing substantial zinc white are now among the most conservation-troubled objects in museum collections.
In the studio
Zinc white is semi-transparent, weak in covering power, and very slow to dry — the opposite of lead in every respect. Used as a tint it is clean and cool; used thickly it is a problem. It reacts with the fatty acids in oil to form zinc soaps, and the resulting paint film becomes hard and brittle over decades, then delaminates: it cracks in a characteristic pattern and can separate cleanly from the layer beneath, taking the picture with it. This was not understood until the late twentieth century, and a great many works were painted in ignorance of it. In watercolour and gouache, where the failure mode does not apply, zinc remains excellent and is still sold as Chinese white.
Afterlife
Titanium white displaced it for general use after 1921, being far more opaque and free of the brittleness problem. Most manufacturers now recommend zinc only in thin tints or in water-based media, and several have removed it from their oil ranges entirely. It survives as an ingredient — many titanium whites contain some zinc to improve handling — and in the conservation literature, where it is the subject of a large and growing body of unhappy research.
Where it appears
Every era and artist in this atlas whose palette includes this pigment.