All grounds that are free of grease and are somewhat absorbent can be used as a ground for painting with water mixable oil paint, providing this has been prepared with a universal primer. The stretched canvas is usually already given this preparation.
Untreated grounds, such as paper, cardboard, wood, cotton and linen, can be prepared with Gesso. This is an excellent universal primer based on pure acrylic.
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.
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.
No, unless this has been universally prepared.
From a technical point of view it is not recommended to paint directly on paper using Cobra. Cobra is a pure oil paint, even though it is possible to mix it with water. The oil would be absorbed by the paper, resulting in the pigments losing their binding. In addition, cracks may appear. The paper therefore has to be first prepared with Gesso.
Oil paint does not adhere well onto metal, plastics and other non-absorbent grounds. The ground will first have to be treated with an adhesive primer or wash primer suitable for the ground in question. These sort of primers can be bought at all reputable stores selling household paints. Once the applied layer of adhesive primer is dry it needs to be sanded lightly. A second layer then has to be applied, which also needs to be sanded lightly once dry. Then apply one or more layers of Gesso. The ground is now ready for painting with oil paint.
This is not recommended. Both products have a surface that is too sealed, so that the oil can scarcely, if at all, bond on the acrylic film. Poor adhesion of the oil paint film would then result.
No, Gesso is a primer based on an acrylic resin dispersion, just as acrylic paint. Acrylic paints do not adhere well onto greasy grounds. Sanding is not recommended either as this, after all, does not change the composition of the ground.