Use mediums to dilute and extend the color strength of acrylic paints. Gloss Medium adds gloss and dries to a durable film. The Matte Medium contains a matting agent which reduces the gloss of paint. These products thin and clean up with water and can be mixed for a satin finish. Thinning acrylics with water can achieve the same dilution of color, but is not recommended because the paint film becomes more fragile.