Paper & Canvas
In theory, watercolours can be used to paint on any type of paper, although the best results will be achieved on watercolour paper. Watercolour paper has a special surface glue, usually gelatine. Because of this glue, the pigments are not absorbed by the paper, which ensures that the colours remain pure. What's more, this glue ensures that when a lot of water is used, the paper does not bulge excessively.
All grounds that are free of grease and are somewhat absorbent, such as paper, cardboard, wood, cotton and linen, can be prepared with Gesso.
When preparing an open woven canvas it is recommended to first apply a layer of Amsterdam acrylic binder. This seals the mesh of the canvas so that the Gesso does not penetrate through to the rear.
If Cobra is thinned with water, universally primed canvases are the best choice. If water is not used, then it is possible to paint on canvases that have been prepared in the traditional way using an oil-based primer.
In theory, every ground can be used, providing it has a sufficient surface structure. Paper is usually used.
When using pastels, a dry coloured powder is spread over the paper. In contrast to paint, pastels do not have a binder that adheres it to the ground. The pastel powder hangs onto the fibres of the paper, as it were. In order to apply a lot of colour, the paper therefore needs a certain surface structure.
Drawing paper, which is suitable for Siberian chalk, for example, is too smooth and/or too hard to hold sufficient pastel.
When other flexible grounds are used, such as textiles, it is important that the painting is framed so that the ground cannot move. Vibrations can cause the pastel particles to loosen.
This has to be due to the quality of the paper. Or it has become damaged when it was cut. With demonstrably straight lines, something has gone wrong with the production of the paper. You must also be careful not to get greasy fingerprints on the paper.