If you use mediums other than acrylic, such as oil, watercolor or gouache, you can still use acrylic to add new effects to your work. Acrylic pastes or gels can be applied as a first layer to any substrate, such as canvas, wood or cardboard to create a new surface ground. A surface ground changes the way paint gets accepted onto the surface. First decide whether you want the ground surface to be absorbent or non-absorbent. Absorbent surfaces are usually matte and will create a soft muted effect, with the paint sinking into the surface. While non-absorbent ground surfaces are usually glossy, and the paint will glide and settle on the top. Both types of surfaces are valid. Once the acrylic gel or paste is applied let it dry overnight. Now paint with your favorite medium but heavily dilute with the appropriate solvent to allow the ground to take effect. For example, if you want to paint with oil, heavily thin the oil paint color with turpentine or mineral spirits so the oil paint becomes runny. Now apply it to the acrylic ground. Scrub the paint in with rags, wipe it off in places, try brushes and knives to get a variety of effects.