Whether you chose the wrong wall color and need to make it lighter, or want to add dimension to a fine art painting, mixing colors can be tricky. You can make any shade lighter with a process called tinting. To make a color lighter, you can add white paint to soften the shade. Mix in small quantities of white at a time so that you don't overdo it. Test your shade continually until you find the perfect hue.
Read the labels on your existing paint can or tube to ascertain the make and kind of your paint. Try to find white paint from the same manufacturer or, at very least, of the same kind. You shouldn't mix acrylic and oils.
Measure 10 percent of the volume of paint you already have in white. If you are painting a wall, and have a 1 gallon can of paint, measure 0.8 pint of white paint.
Pour the white paint into your paint can and mix well with the mixing stick. If you are using tubes of paint, use a palette knife to mix the paint.
Check the shade. The paint should be one to two shades lighter. If it is light enough, continue painting. If you are still not satisfied, continue to add white paint in 10 percent increments. Adding too much white may make it too light, so proceed slowly.