Key Points Note
There are primers and sealers for the base coat, and for the intermediate coat, there are sanding sealers and surfacers. Among the topcoats, those that contain reflective pigments (such as aluminum powder or pearl powder) are composed of a base coat and a clear coat.
Paints for each layer and their raw materials
Primer and sealer paints, known as undercoats, have different roles, so their raw materials and mixing ratios vary. Undercoat paints are typically called “sealers” or “primers,” and their names vary depending on the material being painted. Wood uses wood sealer, while iron uses rust-resistant primer. Sealers serve to prevent the transfer of components from the substrate (hence the term “seal”). On the other hand, primers primarily maintain an alkaline surface on iron to protect it from rust, deactivate it, and attach zinc particles with a high ionization tendency to prevent ionization leaching from the iron surface. The differences in raw material composition for these paints.
Intermediate coating paints have different names. When used for a transparent finish on wood, they are called “Sanding Sealer,” and when used for enamel finishing, they are called “Surfacer.” Sanding Sealer is used to create texture that matches the wood grain and then achieve a smooth surface through polishing. On the other hand, Surfacer, suitable for enamel finishing, ensures a smooth finish through sanding. Additionally, there is a paint known as “Primer-Surfacer” (commonly referred to as “Primer-Surf”) that serves both as rust prevention and surface smoothing, combining two functions in one layer. Surfacer and putty include talc in their composition to form a easily sandable coating. In terms of composition, they are quite similar. Think of Surfacer as paint that allows for spray-on application of putty.