White Lead

WHITE LEAD, the general name for various white mineral pigments soluble in oils, used for durable, long-term painting of various objects and, primarily, interior and exterior walls of buildings. The quality of white lead therefore depends on their coloring power, durability, and resistance to external influences (H₂S contained in the air, smoke, humidity, wind, etc.). Lead white, or basic lead carbonate of various compositions, usually 2PbCO₃.Pb(OH)₂, has long been considered the best in all respects except for color change from H₂S. Since white lead is highly toxic and causes a significant number of occupational poisonings during its manufacture and application, its use is restricted by legislation in all countries. In the USSR, a resolution of the People's Commissariat of Labor dated December 16, 1924, prohibited the opening of new white lead factories, their import from abroad, their sale in dry form (in powder and mortars), and their use for interior painting of premises and for painting various objects. From 1930, all production and use of white lead is prohibited. Lead white can be replaced by: a) lithopone - a mixture of zinc oxide, zinc sulfide, and spar; b) barium white (BaSO₄), added in large quantities to reduce the cost of other more expensive varieties of white lead; c) zinc white (ZnO), already being manufactured in the USSR in a number of plants, and d) titanium white (TiO₂), a paint of the highest quality, produced in large quantities in the U.S.A. and Norway. The question of the large-scale production of the latter in the USSR is now being developed, as ores very rich in TiO₂ have been discovered in the Urals. The replacement of lead white with other harmless varieties has enormous professional-hygienic significance. (For methods of manufacturing white lead and measures to improve this production, see Lead.)