How to Mix Purple Paint. Purple is a vibrant color that comes in many different shades. It is a secondary color that can be mixed by combining two primary colors: red and blue. Purple paint is easily found at an art supply store, but mixing your own purple paint saves you money in the long run and allows you the freedom to create your own perfect shade of paint. Things You'll NeedFind a palette that is suitable for your paint and a paintbrush to mix your paint with. Fill a cup with water and keep it on hand to moisten your brush and help with mixing your paint. Squeeze a small amount of red and blue paint onto your palette. Place your brush in the red paint and spread a small amount on a clean area of your palette. Dip your brush into the blue paint and swirl it around on top of the red paint. This will create the color purple. Add more red or blue paint to your mixture until you find your perfect shade. A plastic palette with cupped areas to contain the paint works well for mixing watercolor paints. Acrylic and oil paints can be mixed on a wooden, plastic or paper palette. Add white to your red and blue paint mixture to create a lighter purple or lavender color. Mix enough purple paint to finish your painting. If you are mixing paint for a large area, note how much blue and red paint you used so you can re-create the same shade of purple. Keep paint and painting supplies out of children's reach.