Tri-Art Artist Mediums have been formulated in accompaniment with Tri-Art Acrylic colours to provide the enterprising artist with the tools needed to create an endless possibility of texture, effects and finishes. These mediums are compatible with each other and all Tri-Art Acrylic colours. They can be mixed together in any proportion to achieve the desired texture, viscosity and finish. The only exception to the rule is Tri-Art Retarder, which is most effective only when used in correct proportion. All Tri-Art Artist Mediums are of archival quality.