# Primer not sticking to new mold-resistant drywall



## jimn (Nov 13, 2010)

No it's not going to seal magically. If the substrate is not bonding then nothing you put on top will either. Not a pro, but it doesn't sound you got all the sanding dust off the wall before painting . But there may be other issues .


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## Gymschu (Dec 12, 2010)

Usually drywall primer is pretty forgiving even if there's some dust still on the surface. Of course, the paint reps will duck responsibility for any problems if the walls weren't absolutely dust free. You could have used a damp sponge mop after vacuuming to get even more of the dust off, but, that doesn't get it all.

At this point you don't have many options. I mean, it's not like you can remove all the primer that's on there now and start over. If it were me, I would lightly sand what's on there now, damp sponge mop the dust off, let it dry, then apply a primer like Zinsser's 1-2-3 which has some "sealing" properties that might just work in this case. I would test it on ONE wall first to see how it's going to work.


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## chrisn (Dec 23, 2007)

Gymschu said:


> Usually drywall primer is pretty forgiving even if there's some dust still on the surface. Of course, the paint reps will duck responsibility for any problems if the walls weren't absolutely dust free. You could have used a damp sponge mop after vacuuming to get even more of the dust off, but, that doesn't get it all.
> 
> At this point you don't have many options. I mean, it's not like you can remove all the primer that's on there now and start over. If it were me, I would lightly sand what's on there now, damp sponge mop the dust off, let it dry, then apply a primer like Zinsser's 1-2-3 which has some "sealing" properties that might just work in this case. I would test it on ONE wall first to see how it's going to work.


That or a coat of Gardz might lock down what is on there.


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## wothersk (Nov 10, 2015)

Gymschu said:


> At this point you don't have many options. I mean, it's not like you can remove all the primer that's on there now and start over. If it were me, I would lightly sand what's on there now, damp sponge mop the dust off, let it dry, then apply a primer like Zinsser's 1-2-3 which has some "sealing" properties that might just work in this case. I would test it on ONE wall first to see how it's going to work.


Thanks, I guess that is probably the best I can do. I'll try a few test areas to see what works.


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## wothersk (Nov 10, 2015)

chrisn said:


> That or a coat of Gardz might lock down what is on there.


You know I wondered about that based on some googling I did looking for solutions to this problem. I actually contacted the Zinsser technical support folks and they told me they didn't think that would work. Based on what I find with my other tests I might pick some up and try it anyway on a small area.


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## Nestor_Kelebay (Jun 17, 2008)

I wouldn't put anything over what you have now. If what you have now isn't sticking well, that's going to be the weak link in the chain, and anything you put over top of it won't strengthen that weak link.

What I would do is buy a roll of 2 inch wide packaging tape, (which has a lot of tack to it) stick it to your primed greenboard and pull it off, thereby removing the primer that isn't sticking.

You said:
While spray painting the ceiling I masked off some of the walls and found that wherever I stuck the green painters tape and then removed it, the primer is getting pulled off with the tape. I don't see the same problem on the regular white drywall.

So, if I understand you correctly, the primer that's not sticking to the greenboard was sprayed on? If so, that could be the problem right there. Spray painting doesn't push the primer right into the porous surface of the drywall like a brush or roller does. That's why painting jobs that involve spray painting always involve "back rolling" the sprayed-on paint or primer so that it's pushed into the porous substrate.

But, I would remove what's not sticking well before you proceed any further.


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## wothersk (Nov 10, 2015)

Nestor_Kelebay said:


> What I would do is buy a roll of 2 inch wide packaging tape, (which has a lot of tack to it) stick it to your primed greenboard and pull it off, thereby removing the primer that isn't sticking.


Interesting idea. Almost 800 sq feet of area to cover though which would be pretty painful. Maybe I should try an area and see how quickly I can progress.



Nestor_Kelebay said:


> So, if I understand you correctly, the primer that's not sticking to the greenboard was sprayed on? If so, that could be the problem right there. Spray painting doesn't push the primer right into the porous surface of the drywall like a brush or roller does. That's why painting jobs that involve spray painting always involve "back rolling" the sprayed-on paint or primer so that it's pushed into the porous substrate.


No, I wasn't very clear in my explanation. The primer was rolled on the walls. The ceiling was sprayed after that (I'm doing something different with my basement, leaving the exposed joists and sprayed them flat black for an industrial look as I don't have very much headroom - it looks great so far)

Thanks for your feedback


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## jeffnc (Apr 1, 2011)

yeah, you're not in a good spot. Taking down the drywall is probably not the worst option right now.

What I would probably do is try to sand all the primer off. Even to the point of damaging the drywall paper slightly. Then cover with Gardz. Then sand again lightly. At this point you're probably good to go with finish painting.


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## wothersk (Nov 10, 2015)

I tested some ideas. I primed some scrap pieces of the green drywall that had never been finished or exposed to drywall dust. I primed three different areas: One with the SW Quali-kote that was used initially, one with the multipurpose primer that SW recommended I try after the fact and one with Zinsser 123. After 36 hour dry time the tape test is pretty clear. Green painters tape pulls off the Quail-kote like it isn't stuck at all. But the tape didn't pull off any of the other two primers at all.

So I don't think drywall dust caused the problem. It seems like I've simply used a bad primer and now I'm stuck with trying to fix it after the fact. So much for going to a paint store to get good advice - this was their recommendation. I didn't ask for a cheap primer - I asked for their recommended primer to do a good job. I've put a lot of work into getting this far and didn't want to cheap out on paint.

I also painted test areas on the existing primed wall, lightly sanding in some areas and not sanding at all in others. Unexpectedly what I found is that the area that I lightly pre-sanded showed no improvement even though the better primer is used - the bad primer remaining underneath still pulls off. But strangely the areas where I didn't sand at all show quite an improvement over the existing situation. It still comes off in small areas but not as much. I'm not sure if the top coat of better primer soaked through to help bond or whether this is simply due to a stronger mechanical layer now that I have two built-up layers. In any event, my initial test suggests that sanding is worse which just doesn't make sense to me. Maybe I didn't sand enough (I stopped where it seemed to be damaging the paper) or maybe I should have wiped it down with a damp rag in addition to vacuuming?

Not sure what to do but I guess I'll bring my test sample back to the SW dealer. Seems like I should be asking for some sort of compensation but I suppose they will find a way to deflect the blame.


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## jeffnc (Apr 1, 2011)

Thanks for the feedback wother. You're an inspiration to DIYers and pros alike! We need more of that kind of experiment.

I would definitely show that to SW and at least get your money back. Never used Quali-cote but it's obviously the problem, not drywall dust (drywall dust is never the problem in my experience, unless it's truly caked on there. Paint manufacturers like to pretend it is though, to cover their ass.)

The problem with warranties in this case is that they only refund the paint cost, not your labor or expense, gas, time, paint removal effort, etc.


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## wothersk (Nov 10, 2015)

jeffnc said:


> Thanks for the feedback wother. You're an inspiration to DIYers and pros alike! We need more of that kind of experiment.


I do wonder whether I'm more concerned than I really need to be? Maybe if I just paint over it then it will be fine and will last 15 years without all peeling off. But how do you know? I'm careful by nature and when I build something I take pride in doing it right. It's upsetting when something like this puts doubt in my plans. Anyway, thanks very much for your responses and hopefully Sherwin Williams will have a good response for me. I will let you know what they suggest.


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## chrisn (Dec 23, 2007)

I would still try the Gardz. It is supposed to soak into( through?) the primer and lock it down. After a coat of that, I would not be afraid to paint over it.


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## wothersk (Nov 10, 2015)

chrisn said:


> I would still try the Gardz. It is supposed to soak into( through?) the primer and lock it down. After a coat of that, I would not be afraid to paint over it.


At this point I'm willing to try anything to save this without having to scrape everything down so yes I'm going to pick up some and try it on a sample section. Thanks


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