Pigment Red 105; formula: Pb3O4
Red lead pigments are one of the oldest and most popular types of anticorrosive pigments, mainly used for primers for metals. They are indirect inhibitors and require reaction with a selected resin system. When used in linseed oil or other oleoresinous binders, they react with acidic groups in the resin and form lead soap, which has an inhibitory effect. They are no longer used in the coating industry due to the toxicity associated with lead.
Basic lead silicochromate is composed of basic lead chromate and basic lead silicate firmly bound to a silica core. It was used in coatings for metal protection in structural steel, and finer grades were used in electrocoat paints. Because these pigments contain both lead and hexavalent chromium, due to toxicity and human health reasons, they have lost their commercial importance.