When used on their own, acrylic paints have a somewhat dead, matte surface which some people find unattractive. You can make them look more like oils by mixing the paints with one of the specific mediums listed bellow. Each of these will slightly change the character of the paint in different ways, so it is worth experimenting with them until you decide which one best meets you needs.
Gloss Medium: An all-purpose mixing medium that increases transparency and gloss and improves the flow of the paint. It can also be used as a final varnish.
Matte Medium: This is an alternative to the gloss medium for those who prefer an eggshell finish. It increases transparency when added to color, and can be used for matte glazes. Not recommended as a final varnish, since it can cause clouding over dark colors.
Gel Medium: When mixed with colors, it increases their transparency and brilliance but does not alter the consistency.
Heavy Gel Medium: Thickens paint while increasing transparency and color brilliance, giving more of the appearance of oil paint. Useful for impasto work, since it holds the marks of the brush and knife well. It will also keep paints workable for longer periods.
Opaque Gel Medium: An economical way to increase paint volume for impasto work. Ir bulks out the paint without affecting the color, And like heavy gel medium it holds the marks of the brush and knife well.
Retarder: When mixed with paint, this slows the drying time. Do not use more than twenty percent of retarder to color, or paint skins may form.
Modeling Paste: Used to build heavy textures and three-dimensional effects on a rigid surface. If mixed with a fifty percent gel medium, the pastet can also be used on canvas or other flexible surfaces. Acrylic colors can be mixed into the paste, or it can be painted over with either acrylic or oils.