Base paint, also known as primer, is used to protect surfaces against rust or to create a good attachment to surfaces such as pure plastic or fiberglass. But to achieve a perfect surface, you should apply a sanding primer or wet-on-wet primer before you start painting. Some primers can be applied directly to the surface, but they are not filling and can cause unevenness that can be seen through the varnish. Here are some examples of different types of base colors and which areas they are best suited for:
It is important to choose the right type of primer for the area you want to use it on to achieve the best result.