Lead driers

Because of the toxicity associated with lead compounds, governmental rulings have severely limited the use of lead drier in coatings. From a performance viewpoint the use of lead in aluminum paint will destroy the leafing characteristics of the film. Coatings containing lead that are exposed to sulfur fumes will discolor. 

Combinations of metal salts arc almost always used. Although mixtures of lead with cobalt and/or manganese are particularly effective, toxicity regulations ban the use of lead driers in consumer paints sold in interstate commerce in the United States, Combinations of cobalt and/or manganese with zirconium, and frequently also with calcium, are commonly used. The amounts of driers needed are very system specific. Their use should be kept to the minimum possible level since they not only catalyze drying but also catalyze the post-drying embrittlement and discoloration reactions. 

Use Dyeing of textiles, waterproofing, varnishes, lead driers, chrome pigments, gold cyanidation process, insecticide, antifouling paints, analytical reagent, hair dye. 

For environmental reasons modern alkyd paints are dried without lead driers and with minimum amounts of cobalt driers [2.80]. Manganese driers are only used in colored paints and corrosion protection coatings because they affect the shade of white and pastel coatings. Special nondiscoloring driers are used to obtain particularly pale white paints or honey-yellow varnishes. 

Lead drier One of many organic lead salts, which are soluble in paints and varnishes used to speed the drying and hardening of the oil vehicle. 

Aluminum Mixing Varnish n Any of the vehicles for aluminum paste or powder which have the property of causing the metallic flakes of the pigment to leaf or float, and that retains this property for an indefinite period of time. They are characterized by low acid number, usually less than 15 but in some specifications, the acid number is required to be less than 7. Ready mixed aluminum vehicles are those that are made without lead drier, used in factory prepared paints, and capable of retention of excellent leafing properties for very long periods of time. Ready-to-mix aluminum vehicles are mixed with aluminum paste or powder, and used within a few hours at the job site. Vehicles... 

Lead driers have traditionally been the most common, although toxicity concerns now severely restriet their use. Lead is a secondary drier as its sole function is to catalyze oxygen uptake. This and its relatively low reactivity make it a good through drier. For this reason it was widely used in combinations with primary driers in the past. It is still used where toxicity and atmospheric sulfide staining do not rule it out. Caleium soaps have been used with lead driers to improve lead solubility and low temperature drying. 

Alkyd Solution (50% solids) Lead Drier (24% lead) Cobalt Drier (12% cobalt) Toluene... 

Lead driers have a toxic effect however, they can be successfully replaced with driers based on zirconium compounds, which function mainly as drier catalysts and thus extend the functional capacity of standard metal driers. 

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