Lead soap driers promote through polymerization of the film, improving its flexibility and its resistance to water and salt at same time. However, since lead driers possess only modest drying properties, they are always combined with Cobalt and/or Manganese, and may be added ata any stage in manufacture. Since Lead soap tends to flocculate with some oils and alkyd resins, it is advisable to add small amounts of calcium driers which stabilizes the Lead, in order to eliminate this drawback.