Painting a Darker Color over Purple
Transitioning from a deep tone to a deeper-toned paint color can be achieved without applying an undercoat of primer. However, even taking a room from purple to black will require two coats of paint. If only one coat of paint is applied, the old color invariably shows through in narrow streaks. The second coat seals any bleeding of the previous color and ensures an even, solid room color. There are some new paint products (like Valspar's Hi-Def paint line) that claim to need only one coat of paint over even color-saturated purple.
Painting a Lighter Color over Purple with Non-colored Primer
Primer comes in white. Primers, such as Kilz, are dual purpose; they seal previous paints to prevent bleeding through new paint colors, and soften especially color-saturated shades such as purple. The importance of toning down a deep or exceptionally brightly colored wall is in the number of coats required when applying the new paint color. Again, even over primer, count on two or three coats of paint to truly cover the old purple paint and the white primer.
Painting a Lighter Color over Purple with Tinted Primer
It is possible to have basic white primer tinted a color very close to the new paint color. Painting over purple with tinted primer may result in needing only one or two coats of new paint. If the underlying tinted primer and new paint colors are applied with care, there should not be a need for a third coat of new paint, no matter how light the new shade is.
Painting a Lighter Color over Purple without Primer
Many consumers find the cost and trouble of buying two different paints, then applying a coat of primer and two coats of new paint just not worth the trouble. Should no primer be used to paint over purple, and using a lighter color for the new paint, plan on applying three coats of paint. The final result will be just as attractive as using an undercoat of primer and two coats of the new paint color. However, if there is any trouble with staining, or other wall conditions that would bleed through, priming with a product with sealer is an absolute preliminary step to painting over purple.