Matte Finish. Rheotech Gel Mediums provide the artist with a thick, buttery acrylic medium ideal for extending colour, as well as creating impasto glazes and texture. Rheotech Gels will dry clear and are nonyellowing. They will mix beautifully with colours and can also be thinned with water for glazing or used as a clear, waterfast seal for sculpture. Their superior adhesive quality also makes them the ideal medium for collage, mixed media, and craft applications.