We apply the primer in many thin layers. We do not try to fully cover with the first coat. The first layer will be as thin as possible (with a brush) or quick with an airbrush. The subsequent layers will gradually cover the model. The many thin layers will help to ensure that even the smallest detail is not lost.
The purpose of priming is to create a surface that is very well adhered to the model (the primer has the property of sticking firmly) and this surface is suitable for the paint that will follow to adhere and lay well. The paints themselves do not have very good adhesion to the materials.
They are ideal for priming plastics, copper, resin, and generally any modeling material. They can be cleaned with water before they dry.
