Pinhead air bubbles in primer

Need some advice. We're repainting our bathroom. Previous owners painted (Very poorly) dark vertical stripes on the walls. You could feel every ridge so we sanded the walls down and patched some areas that were gouged (I suspect there was wallpaper in this room at some point.) Then we primed 2 coats with BIN 123 waterbased primer. Used a standard 3/8" nap roller. The primer developed pin sized air bubbles all over the walls. We've painted a lot and have never had this happen. The texture is so rough that now we need to sand it again. But I'm not sure what to do after that. Any idea what could have caused the bubbles? The adhesion is good, just a texture issue. We did forget to wash down the walls before priming, could that have caused it? If we sand it down again and wash it this time do we need to prime again before painting?

 

Welcome to the forums!

A little hard to say, sight unseen but the #1 cause of bubbles in fresh primer/paint is air in the coating. It can also be caused by contaminants on the substrate and occasionally by errors in the application technique and/or roller used.

First thing you need to do is sand and then reevaluate the wall. It's possible sanding and a coat of paint will fix it but it's also possible you'd need to apply an ultra thin coat of joint compound to fill the 'holes' [you'd sand off all the excess] If that's the case you'd need to reprime.

IMO a 3/8" roller cover is to short for walls. I'd have used a 1/2" nap. I like to apply the paint/primer liberally and then reroll and dress it up once most of the paint is gone from the roller. There shouldn't be any need to wash the walls at this point although you always want to wipe or brush off the sanding dust!

 

I had this problem a few times years ago when I lived and worked in California. In those days all 'wet' areas (laundries, kitchens and bathrooms) were always finished with oil base enamels. Every now and again, I would get these little bubbles in the finish after rolling. I've never figured out exactly what caused except to say it was only on very hot days. We got around this problem by tipping off after rolling, like when you tip off doors. Pain in the xxx but it solved our problem. Hope that helps. I will add ejuasa, you don't need 2 coats of primer, one will suffice. It's only there to help your top coat do whats its supposed to do. Adding a 2nd coat doesn't improve anything. Hope that helps.
Rickaroonie

 

This happened to me too. Two different brands of latex, same colour. No weird conditions or anything, just the two paints didn't get along.

 

Mbisson, yes that 's a strange one. I've painted with 1ooo's of gallons of water base paint in every conceivable way and have never seen that. Sounds like you had some kind of reaction. Hard to pin down not being there. Did you wash the wall with anything? Or add anything to the paint?

Rickaroonie

 

Like Mark said, it's hard to tell without seeing things. You mentioned that the walls may have had wallpaper on them at some point. Did the previous paint job look at least reasonable? Not necessarily in terms of their skill in application, but moreso the texture of the painted surface itself?

I know that if you don't scrub the wallpaper glue off in its entirity as soon as you touch paint/primer to it they get a 'mottled' texture and dry very rough. Not sure if this could have been the culprit. By applying primer to it you'd be in effect reactivating the glue that would have mixed with the previous paint. Just a thought.

I'd consider sanding and reapplying an oil based primer that will bond with the surface but not 'mix' with it.

 

Hey ejuasa, anyway to get a photo posted. Wildbill is onto something there. The rough texture sounds exactly like you didn't remove the residual glue but that doesn't explain the bubbles. A pic might help.

Rick

 

My bubbles happened on a section of 'new' wall as well as the older walls. The new part only had primer and the original latex finish, and the same sized bubbles as the older walls.

I should mention that I was not the one who painted. There was a water leak that did a small amount of damage to my place, and the insurance company brought their own painter in who painted everything, not just the affected spots.


I blame gremlins in the paint lol.


Good news is, if it's wallpaper glue, you can stop that from happening again!