Priming before painting has two purposes: to increase bonding between the surface and the paint, and to hide stains and dark colors so they don’t bleed through.
It’s important to prime before painting:
- Unfinished wood, plywood, particleboard, or MDF
- New drywall or plaster
- Water stains on ceilings
- Knots in wood that have bled through the paint
- Dark or bright paint colors
Primers are available in water-based, oil-based, and shellac-based. Use special stain blocking oil-based or shellac-based primers when painting over knots, water stains, or dark colors. Latex (water-based) primers can be used on new drywall and wood.
Watch this video to find out more.
- Homeowner’s Guide to Paint Primer (article)
- How to Choose the Right Paint Primer (video)
- When to Prime Before You Paint (article)
- How to Prime Exterior Wood Siding (article)
Danny Lipford: The most common questions I hear from people about painting have to do with primer. When do you use it and what kind do you use?
Primers chiefly serve two purposes: they promote bonding and they mask color or stains. Now, anytime you have new wood or drywall, the first coating on it should be a quality primer. This seals the pores of the materials; and, at the same time, creates a surface that is ideal for later coats to bond with.
Primers aren’t made to be durable, but they do help make the more durable coating stick. Stain-blocking primers do just what the name says. They block stains created by wood resins, water, and other materials from bleeding through both themselves and the topcoat.
If you’re painting a ceiling that has had a leak in the past, primer—preferably one that is shellac-based—is a must to prevent those brown water stains from reappearing in the new coating.