Things You'll Need
Palette or mixing bowl
The luminosity of a painting is important to its overall artistic interpretation. Matte or flat finishes are more appropriate for some uses, such as large areas. Most paintings are done with semigloss paint and then coated with either matte or gloss varnish to add luminosity. Oil and acrylic paints, however, can be mixed to gloss, high-gloss or matte luminosity. They can be purchased this way, or mediums can be added to change the finish of the paint.
Squeeze the tube of paint, pushing three-quarters of the desired amount of paint onto the palette. The other 25 percent will be the matte medium that is added.
Add matte medium to the palette at a ratio of one part medium to three parts paint, or 1:3.
Combine the paint and the matte medium well with a palette knife. The medium will not change the hue of the paint, only its luminosity.
Apply a small amount to the painting surface and allow to dry for up to an hour. If the luminosity is flat enough to meet your needs, begin painting. If not, add more matte medium a small amount at a time until the paint reaches a suitable luminosity.