The surface you paint on is almost as important as the painting itself I believe, especially for the longevity of the finished painting and for a professional finish, and having established that I wanted to paint with oils and cold wax on board I did some research online for the best ways to prepare the boards before painting.
I decided to use GAC 100 to seal the wood surface, applying a couple of coats to both sides of the board and the cradle support. GAC 100 is an acrylic polymer medium produced by Golden. It is thin and easy to apply with a brush, drying with a slightly glossy, translucent finish.
I apply two coats to all the surfaces of the board, allowing the final application to dry for at least 2-3 days before the next stage of preparation.
There are several advantages of sealing the boards in this way:
- The GAC 100 stops general moisture seeping into bare wood which may cause the wood to distort and warp. This is why I seal all the surfaces of the board and cradle.
- Sealing also helps to prevent raising of the grain in the wood when the gesso and paint is applied.
- GAC 100 prevents acids from the wood rising to the surface and yellowing light colours of paint application (support induced discolouration or SID)
- Sealing helps to create a smoother surface and stops the first layers of paint sinking into the support too much