Definition: A "primer coat" is a type of paint that is applied as the first layer on a surface before adding other layers of paint. It helps the final paint stick better and can also help cover up any imperfections on the surface.
In advanced discussions, you might talk about the different types of primer coats available, such as oil-based or water-based primers, and when to use each type depending on the surface you are painting.
While there are no specific idioms or phrasal verbs directly related to "primer coat," you might hear the phrase "to lay the groundwork," which means to prepare or set the stage for something important, similar to how a primer coat prepares a surface for final paint.
A "primer coat" is the essential first layer of paint that helps the final layers stick better and look good.