A gel medium is an acrylic resin with water soluble properties. It is used in a variety of works to bring out the luster and add volume to acrylic paint, adjust the transparency, etc., fix collages and produce texture.

The main ingredient of gel medium is acrylic emulsion which is a synthetic resin. Before it hardens, it is a thin water-soluble sticky emulsion but becomes transparent and water-resistant after hardening, has strong adhesive properties and is resistant to light. This ingredient is also included as the principle material (pigment fixing component) in acrylic paint and, with an increase in thickening agent with no pigment included, it becomes a gloss medium, which can be made into a matt medium with a blend of silica or a silica dust. It is also worth noting that a mixture including oxidized titanium and extender pigment produces gesso. This is used in base coats while a firm paste with powdered marble added produces modeling paste used in textures.

When mixed into acrylic paint, gel medium provides transparency and luster (with a matt finish, the luster is subdued) while retaining its viscosity. Because it increases the volume, it makes it easy to produce texture and tactile effects, etc. After a medium has been used to produce tactile effects and the medium has hardened, it is possible to paint over the top. Painting on cloth or wood may be difficult because the paint soaks in. This can be rectified by applying a medium as a base coat or sealer to prevent absorption. In addition to this, the strong adhesiveness of a gel medium makes it possible to bond together a wide range of materials including paper, cloth, wood, polystyrene and acrylic panels, etc. Therefore it is the best choice for use with collages and similar works (the adhesiveness and durability will depend on the type of material). Adding sand or powdered seashell, etc. to the medium and coating the painting will also produce a unique texture effect and by blending with pigment, you can produce your own paint. Adding a little more medium to modeling paste will also prevent cracking.

Do not use gel medium on an oil canvas or over oil paints. However, you can paint with oils over a hardened medium. After using a medium, replace the lid tightly on the container and rinse any residual medium off implements before it hardens. Gel medium can be bought at general art stores.