Do I need to re-prime my walls before painting?
December 9, 2013 12:42 PM   Subscribe

It's been a while since I primed my dining room walls, and I'm not sure if I need to re-prime my walls before painting. Advice paint experts?

About a year and a half ago I stripped my dining room of all wall paper, repaired any damage, and then applied 2 coats of primer. Very good primer and not cheap. The room looked great, but very white. I was now ready to paint the walls my chosen color.

But then, life got in the way, and now, again, a year and a half later, I'm finally ready to paint (water based). As someone that knows very little about painting, should I re-prime the walls?

If the difference will be barely notable, or if it means the paint will looke good for 10 years instead of 12, I'm fine with not re-priming. But if this will make a noticible difference, I will reluctantly re-prime.

Any opinions would be appreciated. I would ask my local paint store, but I'm afraid they would push buying more primer regardless of need.
posted by ratherbethedevil to Home & Garden (15 answers total) 1 user marked this as a favorite
So...The walls are currently just the white primer you put on two years ago? Unless there's some serious marking or damage, you should be just fine putting paint on. No need for yet another coat of primer.
posted by Thorzdad at 12:45 PM on December 9, 2013 [2 favorites]

If you end up choosing a darker color, it might make sense to get a tinted primer.
posted by ROU_Xenophobe at 12:49 PM on December 9, 2013

If nothing else, you really should wash the walls before painting, regardless of whether you re-prime them or not.

(Me ? I'd wash and re-prime, but I'm a bit obsessive there..)
posted by k5.user at 12:52 PM on December 9, 2013 [1 favorite]

Absolutely I would just start on the paint job. I have painted quite a bit of my fixer-upper house. I would dust the walls with a broom (yes walls get dusty) and then simply re-paint. No need for a re-prime. You could wash the walls but don't scrub too hard as you don't want the primer to come off.
posted by St. Peepsburg at 12:59 PM on December 9, 2013 [1 favorite]

Assuming your primer is white and you are painting the walls a light color, you're good to go.

The only reason I can see to prime would be if you are doing a darker color, in which case a tinted primer will help you achieve the desired effect.

You should definitely wash the walls before painting, as you should always do before painting any wall in any context.

FWIW, going forward, you really don't need primer at all if you're painting a light color over another light color. I would potentially prime if I were painting a pale blue room pale yellow or pink, just to keep the colors looking right. But if you're just freshening your ecru dining room wall with more ecru paint, you don't need to prime. You also don't strictly need to prime anytime you're painting over a white wall.
posted by Sara C. at 1:03 PM on December 9, 2013 [2 favorites]

Stuff sticks to primer really well, hence why you prime the walls before you paint. That includes grease and debris. I have painted clean looking walls that I've scrubbed before and had surprise stains still bleed through. Since then - I always prime (personal preference is the KILLZ variety)... In some cases it was probably a waste of $20-$40, but I have to say - I haven't had any uneven stains bleed through since.
posted by Nanukthedog at 1:08 PM on December 9, 2013

You might want to prime depending on the color you'll use, but I'd definitely recommend washing the surface with TSP before painting. It will remove grease and dirt that floats about and collects over the years. You'll get much better end results with painting over a TSP-cleaned wall, in my experience.
posted by Blazecock Pileon at 1:10 PM on December 9, 2013 [5 favorites]

You definitely don't need to prime with something like KILLZ, which is meant for like painting over murals and stuff. If you really feel you need to prime, get the cheapest thing.

I see no reason why paint wouldn't stick to your walls in their current situation.
posted by Sara C. at 1:12 PM on December 9, 2013

The purpose of primer is to establish a surface that paint will work well with. Paint doesn't stick well to super-slick surfaces (like painting over varnished wood), so priming means the paint lasts longer and doesn't peel. Paint soaks in to absorbent surfaces (like painting fresh untreated drywall or plaster) and primer seals that off to the paint can sit on top. Specialized primer can also seal off things like drywall that smells of cigarettes, or pine wood with knots in it (knots seep discoloration that can show through paint). Primer is also good as a really opaque color layer; they can load it with white medium or dark pigment in ways that paint (designed to look pretty and glossy and unfadeable etc) can't handle, but if you're dramatically changing the color of the walls a coat of primer can reduce the number of coats of paint you need. (ex 3 coats of paint, or one primer and one paint).

In your situation, sounds like you don't need new primer at all.

Standard wall-prep for painting is to dust the walls, and if it's a high-traffic area or subject to dirt/steam/cooking oil/etc, wipe down the walls, ideall with a wash containing TSP powder.
posted by aimedwander at 1:13 PM on December 9, 2013 [1 favorite]

Also came in to say TSP. I cannot imagine how you wouldn't be good to go after that.
posted by kmennie at 1:15 PM on December 9, 2013 [1 favorite]

The only instance where I'd recommend you might need to add another bit of primer is if you've got greasy rub spots like you might get from a dog who always contacts the door frame where it passes through, or if there was a LOT of deep frying going on very nearby.

I would definitely vacuum or brush out cobweb corners and do a quick wet-cloth wipedown of the entire surface to clear off dust, though. Dust can definitely interfere with paint adherence, it can also add unwanted 'crumbs' to your paint, and it's a simple enough step to prevent it. /old-house-new-walls experienced professional artist, occasional muralist, habituated to painting on unusual substrates and being paranoid about long term integrity of materials
posted by Lou Stuells at 1:29 PM on December 9, 2013

Yup. Wash with TSP to remove any grease and dust that might inhibit paint binding or affect the finish of your topcoat (primer is by design "stickier" than topcoat, and collects oil and dirt from the air faster than regular paint) and then go ahead and paint with your color of choice. You'll be fine. Don't scrub too hard, primer isn't as abrasion-resistant as topcoat. You shouldn't need to scrub hard anyway unless your walls are super dirty for some reason; TSP is pretty powerful stuff.

You could probably get away with just painting without washing first, but I think the small addition of cost and effort will be well worth it for the peace of mind; also, depending on the environment in that room, there may well have been enough grease-and-dust buildup over the last year and a half to negatively affect the paint binding and/or the look of the final paint job. You definitely don't need to re-prime though, washing with TSP will give you a surface that is basically good as new!

Enjoy your new paint job!
posted by Scientist at 1:54 PM on December 9, 2013

Thanks everyone. Too much good advice to pick a best answer. TSP and then on to painting.

Again, thank you so much.
posted by ratherbethedevil at 2:21 PM on December 9, 2013

As an aside, I am in favor of always priming over old paint, even if I'm painting white on white. (Unless I'm using self-priming topcoat, that is.) I feel that on topcoats that have been sitting out in the air for several years, a new coat of primer provides much better adhesion than just painting over the old topcoat, even if it's been cleaned. It makes for a more durable paintjob in the end. I think that reasonable people can probably disagree about whether the improvement is worth the cost and effort, but I wanted to reassure you that your earlier priming wasn't necessarily a total waste of time and money. It may not have been strictly necessary, but it will still do some good.
posted by Scientist at 4:17 PM on December 9, 2013

Primers have two main purposes. One is to seal the surface and provide base for adhesion, the other is to save money (as primer is cheaper, generally, than paint).

You may need to re-prime depending on what type of primer was used after the wall covering was removed ... so let's go back to the beginning.

Wallpaper destroys walls! There is basically only one way to proceed to avoid problems.

First the wall covering is pulled off, then the glue is scraped, washed, removed to as close to 100% as possible.

Then you need to prime the surface with an oil based primer or paint. Have tried a multitude of waterborne solutions and while products are improving they haven't equaled oil yet. Oil just works without fail. You will also destroy a sleeve and brush, which is a pain, but they aren't worth cleaning.

Glue is your enemy here because it doesn't play well with other water based products. It will impede plasters ability to stick to the underlying surface. Painting unsecured plaster will cause bubbles and the plaster can peel straight off the wall. Glue will also cause your paint to crack as it penetrates the primer and seeks adhesion around the glue.

The oil will seal all the glue that remains, harden up nicks and tears in the drywall paper and make the wall ready to be sanded and repaired (plastered). If there are a lot of repairs (walls pretty much re-glazed) then it would be good to primer the plaster, oil or latex doesn't matter at this point, if there are only a few repairs you can just spot prime them with the finish paint when you start.

If you repaired then latex primed over glue remnants (and there always are) ... it is a disaster waiting for top coat. The problem is glue won't show greatly if latex primed because the primer is porous and has little sheen and if the walls were de-glued really really well, then scuff sanded (with a pole sander and 120 grit sandpaper (less than 5 minutes per wall)) then repaired, then primered, you may be able to get away with only minor problems but problems are to be expected none the less. It can still be rectified (mostly) again with an oil based primer or paint. Oil gives you a solid, clean slate to work with.

Let's pretend the walls were subject to proper prep and product placement previously, now is simply the fun part. Scuff sand (to remove dust and dirt and grease and the sheen of the paint, level imperfections, make the walls smooth to touch and allow yourself to inspect the walls as you move through them. It also provides paint the best chance to adhere possible) then paint, let dry then light scuff (really light, like 2 or 3 minutes per wall) and cut and roll again and if coverage and sheen and smoothness is to your liking ... done :)
posted by phoque at 11:18 PM on December 15, 2013

« Older What to do about a difficult roommate part II   |   .... But I don't want to share by email.... Newer »
This thread is closed to new comments.