Zirconium is a most useful & efficient auxiliary drier. Zirconium like lead serves as a through drier & is generally used in combination with Cobalt, Manganese & Calcium. Unlike Lead, Zirconium is a poor pigment wetting & dispersing agent, hence combination with calcium is necessary.
Zirconium is an active cross-linking agent & as such improves hardness of stoved films as well as their adhesions
Zirconium is not as effective in phenolic resin based media it is recommended as a catalyst for epoxy esters.