A paint base coat is the first layer of paint commonly applied over the primer coat. The color of the paint base coat is often critical in obtaining the proper color from the finished top coat. In some candy-type paints, the paint base coat will determine the depth, shine and refractory ability of the finished paint job. In some modern, two-step automotive painting techniques, the base coat is the color coat for the vehicle, however, the base coat finish is typically dull or flat. The clear coat is applied over the flat base coat and is what gives the finished paint job a glossy effect.

When deciding to paint an item a light color, the use of a light-toned paint base coat will aid in getting the brightest finish possible from the paint. This is due to the paint's inability to completely mask or hide the underlying paint colors. When painting a vehicle bright yellow, for example, it will turn out much brighter and shinier if the yellow is sprayed over a white paint base coat instead of a gray or dark brown primer. This is also true of dark colors, where a dark-colored paint base coat will yield a better finish shade than applying the dark color over a brighter base color. The results are, however, not as drastically affected when painting a dark top coat as compared to using a lighter shade of top coat.

When painting a candy color, such as candy apple red, the paint base coat is critical in determining the finished appearance of the paint job. Silver and gold are the two most commonly used colors to give the clear candy paint the famous wet look. Gold is commonly used when painting a candy apple or candy red look, while silver is the usual choice for creating candy greens and blues. Some of the master painters use a secret mix of golds and silvers. Some of these combinations even contain real gold in the mixture to create the award-winning candy paint jobs seen on show-stopping hot rods and customs.

When painting a house or any type of project, it is imperative that the paint base coat be of the same type of paint as the finish coat. This means that an oil-based paint cannot be used to prime a latex finishing paint and vice-versa. This will result in the finish coat peeling off of the base coat in a short while. It is always necessary to use the same paint base coat as the finish coat to have the best long-lasting results.