Paint primer covers imperfections, conceals stains, neutralizes lower colors, and lets the top coat's color be as true and vibrant as possible. Paint primers can be used for both interior and exterior paints.
Here's what you need to know to apply an effective primer coat and start your painting job on the right foot.
Reasons to Prime Before Painting
- Stabilizes substrate: Paint primer provides a stable texture for the paint to grab onto.
- Covers stains: Primer covers stains. This lets paint do the job of displaying colors, not masking stains.
- Neutralizes colors: Primer neutralizes color coats when painting light colors over dark colors.
- Minimizes color coats: Fewer paint coats are needed when primer is used, and primer is usually less expensive than paint.
When to Use Paint Primer
Primer isn't always required. But if you encounter any of these situations, the color coating will look better and last longer if you add primer first:
- Porous surface: A porous surface, whether bare wood, masonry, or an existing paint coat, requires a primer.
- Unfinished drywall: New or otherwise unfinished drywallis porous, too. Not only is the face paper on the drywall porous but so too is the joint compound in the seams.
- Glossy paint: Scuffing a glossy sheen helps the next coating stick better. Using a primer also helps paint stick to glossy surfaces.
- Color coat change: When changing paint colors, adding one or two layers of white primer eases the color change. Even better, tint the primer the paint color.
- Stains: Spotted or stained surfaces benefit from a coat or two of primer before painting. Consider using thicker primers such as Kilz 2 or Kilz Max.
- Skim-coats: A skim coat is a thin swipe of drywall compound laid over bare drywall.Skim coats aren't common, but they are highly porous and thus require at least one coat of primer.
When Not to Use Paint Primer
While priming is usually the safest option, you can often get by without priming if:
- Walls are clean: If your walls are clean and in good condition, you might be able to eliminate the need for primer. Clean the walls before painting with tri-sodium phosphate (TSP) and water. Or clean without water with a brush attachment on a shop vacuum to remove major debris like cobwebs and dust.
- Surface is less porous: All surfaces have pores. But previously coated surfaces are relatively low porous and shouldn't require priming, unless they are glossy or stained.
- Colors aren't changing much: If the previous color and the new color are the same or close, you may be able to paint directly on top.
Types of Paint Primer
Depending on your surface, different types of primers will work best for your project. There are three main types of primers: water-based (latex), oil-based, and shellac primers.
- Water-based primers: A latex-based primer is the safest since it comes in low- or no-VOC options. Water-based latex primers are generally easy to clean from your paint brushes and other supplies. You can use latex-based primer on drywall, wood, brick, and other materials.
- Oil-based primers: Oil-based primers can be applied under oil-based or water-based paints. These primers provide thick coverage and typically stop any stains on the wall from showing through. Note that they are slow-drying and can release VOCs.
- Shellac primers: When you have a serious coverage project involving stains, smoke, smells, and other issues, a shellac primer could be the way to go. Shellac primers release VOCs.
How Much Paint Primer You Need
This helpful paint calculator acts as a guide for how much paint primer to buy before starting your project.
If You’re Using Self-Priming Paint
Self-priming paintis essentially a paint that is thicker than regular paint. Because it is thicker, it builds up higher and forms a thicker coat. It is preferable to use a separate primer and paint. But if the walls are basically in good condition, you can use a combination paint and primer.
Self-priming paint is not a miracle cure. Laying down a thicker paint build makes for a weaker coat that takes longer to dry.
Additionally, the higher per-unit cost and the possible need for more than the advertised single coat mean that it may not be a money- or time-saver.
Common Paint Primer Colors
Paint primer is usually white, but you can tint it the same color as the top coat to reduce the number of color coats needed.
Tinted primer lets the color stand on its own, without competing against bottom colors.
Pre-tinted primers are available, too. Tinted primers come in various shades of gray, as well as some reds, greens, browns, and tans.
FAQ
What happens if you don’t use primer before painting?
See AlsoWhat is Primer Paint?If you don't use a primer before painting, you could face a paint job that isn't going to last as long or look as good as it could. Without proper preparation, your paint could bubble, peel, look textured, or it could let stains show through.
Is paint primer necessary?
Unless you have a paint with primer in it or a wall that is totally smooth and uniform in color, a paint primer is necessary for a coat of paint that looks professional.
How many coats of primer do you need?
Typically, two coats of primer are sufficient. However, if your wall has more serious issues, such as staining or rough patches, three may be necessary. Even using primer, you'll still want to apply the customary two coats of paint to the surface.
How long does paint primer last?
Paint primer on an interior wall can last for years before applying the color coat, as long as the primer is kept dry and clean. Paint primer on an exterior wall may last up to a year prior to painting the home. But it will likely need to be washed first. The shelf life of paint primer is two years.
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