Can I paint oil over latex?

[AMCguy]

I painted the inside of my garage with white latex primer and then paint. I should also mention that the walls and ceiling are fir plywood. It looked good for the first year, but now the paint has just turned brown over the knots. You can also see several big streaks of brown on almost every sheet. I've been told these are tannins from the wood that will almost always bleed through latex.

I now know I should have gone with oil. I wish the paint store told me this when I was buying my paint. I spent a **** ton of money there. I'm willing to go through another round of painting, but only if I'm going to get the desired result. It's going to be a major pain with all the things I'm going to have to move.

I have heard You can apply oil over latex but you can't apply latex over oil. Is it folk lore or can I indeed apply oil over latex? I know paint has changed a lot over the years.

 

[Dan in Pasadena]

I sold paint retail for a number of years back in the day. The rule of thumb has always been as you stated. No latex over oil without sanding and priming.

There's nothing wrong with latex paint over wood with tannins, if it's the RIGHT latex meaning a good quality primer such as Kilz that is made for it. A primer made for the purpose will sometimes absorb the tannins into its paint film as a way to neutralize it's staining properties, hence the brown staining.

If the latex is a stain-absorbing primer that's adhering properly there's no reason you can't paint over it with EITHER a quality latex or oil based paint as a top coat. If the latex is not a primer made for dealing with stains, those stains will likely transfer through whatever finish coat you apply meaning you need to primer it with a proper primer. By the way, the best Kilz (IMHO) is the alcohol based kind (aka shellac based) it will kill the tannins very well.

 

[alwaysFlOoReD]

I was going to say to use a shellac. You used to be able to buy dry shellac and add your own alcohol and tint to make your own primer. I've used clear shellac to cover stains on the ceiling from a leaking roof then paint, it worked well.

Richard

 

[Bigplum]

Find a latex paint in the same colour as the stains.....

 

[AnEv942]

Simply applying paint whether latex or oil won't solve the problem. Nor would have using oil originally. For tannins, pitch etc its the primer-specifically designed for that, stain blocking. I'm partial to oil base products but a lot of the current water base are equal to if not better in some cases.

You didn't mention if latex paint is flat wall or enamel. In ether case to stop the bleed thru you need to use a quality primer. I've had very good luck with Zinssers primers-specifically High Hide cover-stain-Its a stain blocker and bond coat. When switching materials the bond coat really helps adhesion. Especially if repainting enamel, though doors, frames or anything that will see high contact should still be sanded.
As to the oil over latex/ latex over oil, yes you can get a way with less prep oil over latex and generally will have good results. Applying latex over oil with out serious prep, (washing,sanding) can lead to disaster. Usually it''ll just peel off without much effort. Ive redone kitchens that folks painted-you could peel off sections like saran wrap.

Bottom line though if its bleeding that bad if me I would reprime with a stain block/bond coat primer. Simply top coating with oil base 'paint' will not stop the bleed-might take a little longer but will discolor-. As this is old work Id stay with water base stain block/bond coat though primer could be oil, specifically Zinssers 03551, Last few time I use Kilz wasnt impressed. Id top coat water base, just to make life easier down the road come repaint time.

 

[theoldwizard1]

There's nothing wrong with latex paint over wood with tannins, if it's the RIGHT latex meaning a good quality primer such as Kilz that is made for it. A primer made for the purpose will sometimes absorb the tannins into its paint film as a way to neutralize it's staining properties, hence the brown staining.

Kilz make dozens of different primers now a days. I would use Kilz Original. You can get it in a spray can Just rough up the areas with knots/stain with some medium sand paper and spray. Follow directions on the can. A second coat of primer wouldn't hurt because you ar only doing the knots/stains.

Top coat with latex.

 

[djjsr]

The shellac based primer works well!!!! I've been using it to seal knots and water stains. Two coats, dries fast. Great stuff.

You don't have to cover the whole wall with it. Just get a quart and hit the stained areas.

 

[CNGsaves]

+1 for Zinsser or Kiltz primer. Sand a little first on the worse spots, then apply 2 or even 3 coats of primer. Good luck.

 

[rlitman]

Kilz make dozens of different primers now a days. I would use Kilz Original.

Kilz original is oil based. I've had good luck with it hiding knots in wood, and it is my go-to primer for wood. Being oil based, I can paint in my shop in the winter, below freezing temperatures. Don't try that with latex.

The shellac based primer works well!!!!

These can be great at hiding some things (like knots that would bleed through), and not so great at hiding other things. I had a red stain that came through several coats of paint, that oil based primer stopped, when shellac based primer did not.

Shellac based primer will stick to anything, and stick better than just about anything else. That can be a big plus. But it is also no good for exterior use.

 

[AMCguy]

Thank you for the advice. My local hardware store has the full line of both Kilz and Zinsser primers and a very good selection of paint. I'll be shopping there, not the paint store that gave me bad advice. I'm not crazy about having to start from the beginning though. I had hoped a final coat of the good stuff would do the trick. Oh well. Live and learn.

 

[djjsr]

I had a red stain that came through several coats of paint, that oil based primer stopped, when shellac based primer did not.

The cop shows on TV say to use bleach.

 

[rlitman]

The cop shows on TV say to use bleach.

Nice one! You almost got me to spit iced tea all over my keyboard!
I had to cup my hand to my mouth.

I'm not sure what it was, as someone had already painted over it rather than clean it. But it looked like a streak of lipstick, or crayon, or something like that.
Whatever it was, it kept coming right through the paint. Sometimes after a few weeks, sometimes it took months.