Function

• The function of a primer is to provide a barrier to keep moisture from the surface of a material. When the moisture comes into contact with the surface, rust is more likely to form if there is no protective coating.
  
  

Types

• Some types of primers are made solely for a particular material like metal. Some primers are rust-proof or rust-inhibiting. Other primers combine with paint, such as those used for cars or metal furniture.
  
  

Features

• Good primers are easy to apply. Most need only a paintbrush for application. For rust spots, a small paintbrush will do.
  
  

Significance

• Most objects are manufactured with a primer. But as time passes, the clear coating wears off, leaving the object susceptible to a rust spot.