Mediums and Additives offer artists infinite control of changing acrylic colors. They range in consistency from pourable to moldable. They may be used to create glazes, extend paints, build texture, change finishes and work as a gluing agent for collages. Because there are so many to choose from, an artist first needs to determine which characteristic(s) they are looking to change. They include Gel Mediums, Pastes, Polymers and Varnishes.