Zinc White
Zinc white was initially introduced as a water-colour paint and was first adopted as a pigment in paint by artists in the 19th century. A cross section of paint from Ophelia (1852) under UV light shows the layer of zinc white applied by the English painter and illustrator John Everett Millais (1829-1896) over the lead white ground.
Field's Chromatography or Treatise on Colours and Pigments as Used by Artists
ZINC WHITE
"Is either the anhydrous oxide, the hydrate oxide, or hydrated basic carbonate of zinc. It varies in opacity and colour according to the mode of manufacture, and the purity of the compound, but may always be relied upon as permanent. The whiteness of the best samples rivals that of lead white, and it is not tarnished like the latter by sulphurous vapours. In opacity it never equals lead white, and might perhaps serve advantageously as a glaze over that pigment, either alone or compounded with other colours; as well as act as a medium of interposition between lead white and those colours which are injured by it, such as gamboge, crimson lake, etc. When duly and skilfully prepared the colour and body of this pigment are sufficient to qualify it for a general use upon the palette in oil: in water it has been superseded by Chinese white. "Occasionally, starch, chalk, white clay, and carbonate of baryta, are employed as adulterants; none of which, however, are inimical to stability.
"As a pigment, zinc white may be said to be innoxious. As oxide of zinc does not readily form a saponaceous compound with fats or oil like lead white, the paint prepared with it and ordinary linseed oil does not dry or harden so rapidly. For the purpose of causing it to be more siccative, the oil was boiled with a large quantity of litharge, but by this method the white was liable to tarnish on meeting with foul air. Instead of litharge, experiments have led to the choice of salts of zinc, such as the chloride or sulphate, a small percentage of which, on being mixed with the oil or oxide, confers upon it the property of rapidly hardening. The same result is attained by employing an oil, dried by boiling with about five per cent of peroxide of manganese. In either case, a paint retaining its white colour permanently is produced. These agents might, with advantage, be more generally used in the place of litharge for rendering oils siccative. Many pigments which are not naturally affected by sulphurous emanations are apt to suffer if mixed with an oil made drying by means of lead."
Timeline
- In the 1780's Guyton de Morveau was asked by the French government to find a replacement pigment for lead white. He recommended zinc oxide is a suitable material that had been known of for a long time. Zinc white, is non-toxic and has the advantage of not darkening in the presence of sulphurous gases as lead carbonate does when it is converted to black lead sulphide.
- 1834 - The London firm Winsor and Newton Ltd., introduced a particularly dense form of zinc oxide, which was sold as Chinese white. Zinc white suffered from the disadvantages that it dried very slowly as an oil pigment and its covering power was not great. It was however a safer alternative to the lead white, widely used by artists of the time.
- By 1849 the status of zinc white was considered good enough for for the French Minister of Public Works to issue a decree cautioning against the use of lead white. mass production of zinc white also resulted in its price falling to the same level as cheap lead white.
