Homeowner’s Guide to Paint Primer
Painting & Finishing by Jerri Farris
Primers are specially formulated paint products that are used to prepare surfaces for the finish coat of paint. Their most important job is to adhere to the substrate while creating a uniform surface that is ready to receive paint. Primers also act to seal pores in wood and other permeable materials as well as to prevent stains, knots, and wood tannins from bleeding through. When properly applied, primers can make your paint job last longer and look better.
When to Prime
Every unfinished surface—including wood, drywall, metal, and concrete—should be primed before painting. While it can be tempting to skip this step, the results are almost always disappointing. Paint applied to unprimed surfaces tends to peel, crack, and chalk more than paint applied to properly primed surfaces.
Previously painted surfaces may not require priming unless you’re switching between oil-based or latex paint, or the existing paint is failing. Always scrape and sand any deteriorating surfaces before applying primer. Remember, your paint job is no better than the preparation that goes into it.
While it used to be necessary to apply oil-based primers over oil-based paint and latex primers over latex paints, many primers today allow you to switch between them as long as you prepare the surface properly. When painting over interior oil-based woodwork with latex, be sure to sand or degloss the surface first, then paint with a bonding primer before topcoating with latex. Painting over multiple layers of oil-based paint on the outside of older homes with latex paint can cause adhesion problems, so in that situation, you’re better to continue using oil-based house paint.
At first glance applying primer may seem like an unnecessary expense, but it actually saves money as well as time. A good coat of primer improves paint’s hide, or ability to cover, reducing the number of coats that are necessary to achieve a smooth finish. Primers can be tinted to match the paint color. Tinting improves the primer’s hide and smoothes the transition between primer and topcoat.
Types of Primers
Primers are available in oil, shellac, or latex-based formulas. Each type has differing properties and uses a different solvent for thinning and cleanup. Choosing which type to use is largely a matter of matching the primer’s characteristics to the project at hand.
Oil Primers
These slow drying primers release volatile organic compounds in the air and require mineral spirits for cleanup and thinning. They produce a very smooth finish that does the best job of filling pores in bare wood while not raising the grain. Oil primers also provide a good barrier to keep tannins from certain woods from bleeding through.
Oil primers are good to use for:
- Unfinished wood.
- Previously varnished wood.
- Redwood, cedar, or other woods that tend to bleed tannins.
- Heavily weathered wood.
- Over existing paint that is failing due to chalking or cracking.
Latex primers
These fast drying, water-soluble primers have come along way in recent years and are now available in low and no-VOC formulas. Latex primers are not as brittle as their oil or shellac-based cousins and provide a more flexible finish that is resistant to cracking. This makes them suitable for priming bare softwoods, though test them first to see if they raise the grain or allow resin to bleed through. Latex primers are the best choice for unfinished drywall, since they act to even out the texture and sheen between the wallboard and joint compound. They also allow water vapor to pass through, which can make them less likely to peel.
Use latex primers on:
- Unfinished drywall.
- Bare softwoods like pine.
- Masonry such as brick or concrete block.
- Galvanized metal, after proper cleaning.
If you’re not sure whether the existing paint is oil-based or latex, wipe a small area with a clean rag saturated with denatured alcohol, paint deglosser, or non-acetone fingernail polish remover. If the paint is oil-based, it won’t be affected. If it’s latex, some paint will come off on the rag or the surface will become tacky.
Pigmented Shellac Primers
Shellac-based primers are fast drying and use denatured alcohol for thinning and cleanup. Though smelly and difficult to use, they are excellent at blocking stains and preventing bleed through.
Shellac primers should be used to prime or spot prime:
- Water, smoke, and rust stains.
- Knots, pitch pockets, and stubborn tannin bleeding.
- Wood, metal, plaster, or plastic when you need a fast drying product.
Application and Clean Up
All primers should be applied to clean, dry, grease-free surfaces. It is a good idea to lightly sand surfaces—followed by wiping off any dust with a tack rag or damp cloth—before applying primer. If the primer leaves the surface rough, lightly sand and dust it again before applying the finish coat. For best results, paint surfaces within a week after priming.
Make sure you have adequate ventilation when using any paint product. This means that there should be no more of the fumes in the room than if you were working outside. If opening the windows and using fans isn’t enough, wear a mask or respirator. You might also want to consider using one of the new low or non-VOC latex formulations when painting indoors.
For more information on specific primers, visit the Kilz and Zinsser websites.
27 Comments on “Homeowner’s Guide to Paint Primer”
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February 29th, 2008 at 02:31
Shellac-based primers are fast drying and use denatured alcohol for thinning and cleanup. Though smelly and difficult to use, they are excellent at blocking stains and preventing bleed through.
June 18th, 2008 at 15:31
Can I apply an oil-based sealer over a coat of latex paint and two coats of latex primer? I am painting an antique dresser, and the tannin in the wood seems to be bleeding through.
Ben Erickson Says:June 19th, 2008 at 15:36
Hi Pam,
I’ve had similar problems in the past, and while I can’t speak for every brand of sealer, you can prime over latex paint with Zinsser B-I-N (a shellac based product) and Cover-Stain (an oil based product). They also both come in spray cans if you just need to spot prime a few spots.
June 30th, 2008 at 14:08
I plan to paint a bedroom and noticed the current paint has little cracks you see when you look closely. The prior owner may have had wallpaper prior to the current paint…would cracks indicate the walls weren’t cleaned well after removing the wallpaper?
Is the best solution to prime before repainting?
Any suggestions would be helpful.
Thank you.
July 2nd, 2008 at 23:56
I used an oil based primer to prime the walls in my bathroom. I didn’t realize how much mess it would make. How do I clean the primer that has splattered on the tub, and toilet?
Thanks in advance for your help!
Ben Erickson Says:July 8th, 2008 at 13:38
Amanda,
Try using a paint scraper that holds a single edged razor blade.
August 19th, 2008 at 16:01
I have an exterior deck. Built with preserved wood, 4 years ago. It has been sealed with Thompson’s Water Seal twice. The last time 2 years ago.
I wish to paint the top, side rails, etc. (not the deck floor) white. I have been told to prime with exterior oil based primer then top coat with exterior latex.
Any suggestions?
Thank you
October 6th, 2008 at 23:56
The laminate on our kitchen cabinets is coming off I guess it’s old. The contact cement underneath appears to be dried out and seems to come off easily when sanded. I’ve tought about removing all of the laminate and then priming and painting the wood. (There’s actually wood, not particle board underneath the laminate). Do you have a suggestion for a primer/sealer and paint combination?
October 8th, 2008 at 12:04
I have a problem exterior window that gets scorched by the sun and blowing rain and snow. I have completely stripped off all layers of paint.
Instead of using oil based primer could I use a solid color
oil based stain and then use a gloss oil paint?
Any suggestion?
Thanks
Lori
January 3rd, 2009 at 18:58
I have a bed that I used polyshade stain and polyurthane on and I would like to paint over it with white Kiltz paint.The bed is a cherry color. Would I have to use a primer to keep the cherry color from bleeding through? Tell me if I can paint over stain
March 4th, 2009 at 17:39
Edna, I would use a Kiltz primer to prevent bleeding. I am just an amateur woodworker
July 9th, 2009 at 15:25
after applying an oil based primer, how long should I wait before painting ?
Ben Erickson Says:July 10th, 2009 at 08:02
Hi Nancy,
That will depend on the temperature, humidity, and particular product you’re using. Some can be painted over in as little as an hour, while others will need to dry overnight. Check the directions on the product you plan to use for more information.
July 25th, 2009 at 23:57
I am painting over doors and trim that were painted with oil 12 years ago, I lightly sanded, primed with Kilz 2 and applied one coat of Dunn Edwards latex semi-gloss. I is now peeling off like I didn’t do any prepping. What do I do now!
Do I have to sand it all off now or is there something I can just paint over the Kilz 2 with?
A very frustrated and tired homeowner!
Ben Erickson Says:August 4th, 2009 at 10:38
Hi Dorothy,
If possible, you’re probably better off removing it, being sure it’s sanded enough to take the gloss off, then repriming with an oil-based primer.
August 7th, 2009 at 16:59
I primed a painted ceiling.I roughed it up with sandpaper,
cleaned it off. Primed it,I felt it needed a second coat.
I noticed a bubble, it looked like a big boil. Should I sand
the area and reprime it? Thank You, Bill
August 31st, 2009 at 19:33
I am painting the outside of my house. The paint is flaking and bare wood is showing. I am going to use a lightly tinted primer. Why do I have to paint over it? It looks nice the way it is. Can I leave it with only the primer and forget about the paint? I live in Oregon where it rains a lot.
Ben Erickson Says:September 1st, 2009 at 13:39
Hi Marianne,
Primer isn’t formulated to hold up against direct exposure to the elements. To find out more, read Danny’s answer to a similiar question at Can Primer Be Used as the Finish Coat When Painting?.
December 27th, 2009 at 17:30
I am a professional painter and want to know if anyone knows of any waterbase primer that will not raise the grain of wood. Or at least one with minimal raising.
January 8th, 2010 at 12:05
We’ve just painted a ceiling with oil-based primer over a wall-papered ceiling and a coat of paint. It look as though Home Depot misinformed us about the primer. The guy said it was okay if the primer was transparent in areas but I’m seeing shadows now when I walk in the room from a certain direction and it looks like a dirty ceiling. Can we reprime and paint that? Thanks if you can answer us.
February 11th, 2010 at 05:55
We painted our ceiling that had a water spot with Zinsser oil based primer. After it dry we painted the whole ceiling with ceiling paint. But the very next day after the paint is dry the spots that we use primer cannot be cover up with paint no matter how many time we paint it. What had gone wrong? What can we do now? We really desperate for an answer. Hope you can answer us please.
February 24th, 2010 at 20:09
I would like to verify that I can use an oil based primer under a latex paint ( exterior) in a high humidity, tropical environment? Any information would be greatly appreciated.
Ben Erickson Says:February 25th, 2010 at 09:25
Hi Robert,
You can use an oil based primer under a latex paint, but if it’s very humid, it will take a long time (probably days at least) to dry. If possible, I would wait until the weather is less humid before painting with oil based.
March 3rd, 2010 at 05:36
I WANT TO PRIME & PAIANT WITH LATEX PRODUCTS THE DRYWALL ON A NEW CONSTRUCTION HOME. IT IS ACCEPTABLE TO MIX THE PAINT AND THE PRIMER AND APPLY IN ONE APPLICATION?.
Ben Erickson Says:March 3rd, 2010 at 17:20
Hi Lynwood,
If you’re trying to match the color of the primer to the color of the finished coat, you should have the paint store add colorant to the primer to tint it closer to the final color rather than mixing the primer and topcoat together.
March 4th, 2010 at 14:02
I live in Florida. I primed the house a year ago. Do I need to re prime the house before I paint or can I pressure wash it before?
Ben Erickson Says:March 5th, 2010 at 09:36
Hi Nikk,
I assume you’re talking about the outside of a house. If you primed it a year ago and didn’t go back and topcoat it with exterior paint within the time period recommended by the paint manufacturer, you would probably need to clean it thoroughly and reprime before painting, since primer should be topcoated within a set period of time. Your best is to contact the company that made the primer and see what they recommend.