Is there something about a primer that makes it stick better than other paints of the same brand? I always just figured it was a neutral colour base so that the top coat looks uniform.
Craig
You know, I have never found anything which specifically stated that a generic primer actually improves paint adhesion.
To me primer is usually used as a uniform neutral-color base coat for the final coat of paint. Especially if the model is made from several different materials. Primers are very opaque so they can produce uniform base color, even if they are covering highly contrasting surfaces. Also when a smooth surface is desired, the flat and even color will show any imperfections so they can be repaired and then primed again. That to me is the main use for primers.
But there are also some specialized primers. I have self-etching primer which supposedly adheres very well to metal surfaces providing a very good bond between the metal surface and the top coat of paint. Other than the self-etching property (whatever that means chemically), it has an appearance of a standard opaque gray primer.
Then there are adhesion promoting primers specifically designed to improve bond between a flexible plastic surface and the top coat of paint. Those are usually transparent in color.
I try to avoid primers whenever possible to minimize the thickness of paint on the model. But sometimes it is unavoidable. Like a yellow-plastic model which has to be painted white. Without opaque white primer the yellow plastic would show through the white paint. Same goes for dark color plastic shell which has to be painted with a light color. Or if a shell has metal and plastic parts of very different colors and it needs to be painted using a light color paint. It needs a coat of light color primer.
