If you’ve spent any time painting your home, you probably know that most surfaces need at least one coat of primer before you can add any paint. Using the right type and amount of primer ensures a vibrant, even color that stands the test of time. But how many coats of primer are really necessary?
The answer depends on what you’re painting, but most projects only need one or two coats of primer. If you’re new to DIY painting, read on to learn all the ins and outs of primer coats before you pick up your brush and start painting.
Why the Right Amount of Primer Matters
Primer contains a mixture of solvents, resins, and some pigments, but its primary function is to seal porous surfaces. This allows the paint to cover the surface more evenly, adhere better, and last longer. It also limits the amount of paint a surface absorbs, protecting the substrate and reducing the amount of paint needed for an even finish.
Skipping primer altogether or using too little allows the surface to soak up too much paint, resulting in a dull, blotchy appearance. On the other hand, using too much primer can cause cracking, chipping, long drying times, and potential damage to drywall.
Some homeowners think they haven’t used enough primer when they really have. It’s normal for some of the old base colors to show through the dry primer, but the primer will prevent this color from bleeding into the new paint.
Choosing the Right Primer
Selecting the right kind of primer is just as important as applying the correct amount. Different surfaces and paint types require specific primers:
- For heavily stained surfaces or those with wallpaper glue residue, a stain-killing primer is ideal.
- Masonry and concrete often need a separate sealer before primer application.
- Match the primer type (oil-based or water-based) to the paint you’re using for best results.
If you use a primer that’s not suited for the surface you’re painting, you may get sub-par results.
When To Use One Coat of Primer
A single coat of primer is often enough in the following situations:
Painting Over Light Colors
When painting over white or very light paint, one coat of primer is usually enough. The surface is already prepared to accept another layer of paint, and there’s no risk of the base coat showing through.
Covering Medium or Light Tones
If you’re covering medium-light tones like sky blue or mint green with white or another very light color, start with one layer of primer. If the old color still shows through after drying, you may need to add a second coat.
Using Tinted Primer
Tinted primer can often reduce the number of coats needed from two to one by neutralizing the underlying color. While factory-tinted primer isn’t always available on shelves, most paint stores can tint primer on request.
However, adding pigment to a primer can reduce the primer’s ability to create a smooth surface, so be careful not to overdo it.
Previously Painted Surfaces in Good Condition
If you’re painting a surface that you’ve already painted before and it’s still in good shape, one coat of primer should be enough. The old paint works as a base, reducing the absorption of the new paint and making sure the new paint adheres.
Self-priming paint, as the name implies, doesn’t require a primer, but there’s no harm in using one coat as a base.
When To Use Two Coats of Primer
Most unpainted surfaces benefit from two coats of primer. This is because different areas of an unprimed surface may have varying levels of porosity, which can lead to uneven paint absorption and a blotchy finish. The first coat of primer is absorbed by the surface, while the second coat fills in any remaining thin spots.
When in doubt, use two coats of primer on the following surfaces:
Wood Surfaces
If you’re painting on bare wood that’s never had any paint on it before, we recommend using two coats of primer. Oil-based primers generally perform better on bare wood, but water-based primers can work well on smooth softwood surfaces. For painted wood, use an oil-based primer.
Start by applying the first coat of primer. Allow it to dry for 12 to 24 hours (if you’re using an oil-based primer) or one to two hours (if you’re using a water-based primer). Then, apply the second coat.
Medium-Density Fiberboard (MDF)
For painting MDF, first seal the edges. Then, apply two or three coats of oil-based primer (avoid water-based primers, which can roughen the fibers). Finish by allowing at least 24 hours of drying time between coats.
Drywall
For drywall, start with one coat of drywall primer-sealer and allow it to fully dry. Then, check for imperfections like bumps, nicks, or thin spots, applying a second coat if necessary.
Plaster
Plaster is prone to lime stains that can bleed through paint. But, if you use an oil-based stain-blocking primer, apply just one coat, and let it dry for 12 to 24 hours before applying the second coat, you should be in the clear.
Masonry
For masonry surfaces, start with one coat of water-based latex primer, then allow one to two hours of drying time. If stains, mildew, or efflorescence are visible, add a second coat. You can always use a stain-killing primer for prominent stains.
Concrete
Concrete surfaces typically require two coats of water-based primer, but there are other options. Acrylic primer, polyurethane, and epoxy are all popular alternatives that work well.
Most primers are dry to the touch within a few hours, but for best results, wait at least eight hours before applying your final coat of paint over a water-based primer and 24 hours before painting over an oil-based primer.
Application Tips
A successful paint job goes beyond just the number of coats you use. Here are some additional tips to get a crisp finish:
- Thoroughly clean the surface before priming to remove dust, dirt, and oils.
- Use high-quality brushes and rollers to apply primer evenly.
- Mix the primer well before use.
- Follow the manufacturer’s instructions.
- Consider humidity and temperature when determining drying times.
Always paint in a well-ventilated area. Paint fumes can be harmful, especially in apartment buildings with shared ventilation systems. For more painting safety information, refer to the United States Environmental Protection Agency’s guide on healthy indoor painting practices.
Final Thoughts About Applying Primer
Applying the right amount of primer is the first step toward getting a professional-looking paint job. It’s easy to rush your painting, but if you take your time, you’ll get better results. Instead of having to go back and repaint, use the right amount of primer the first time. Then, you can reap the benefits of your vibrant paint job for years to come.
