# skimcoat and paper tape problems



## nuge (Mar 16, 2010)

I am not a contractor--just a diy homeowner looking for a couple of solutions.

I've done a lot of taping with self-adhesive mesh tape. Seams around doors and windows eventually "pop" out so I thought I'd try paper tape. I think I've figured out why I get some larger bubbles and later peeling with paper tape--not enough JC underneath, right? One problem I haven't solved is why I get a fine, hairline crack around the edges of the tape and along that center fold line when I come back to sand and add another coat. Why is this? Sometimes it comes through additional layers of JC.

Also, I've been skim coating to fill in dings from scraping wallpaper. I lightly sand then vacuum dust and wipe down before priming. Everything goes great during the prime and 1st coat of paint. At the 2nd coat of paint, I get tiny bubbles pushing the paint out that go back to the skim coat layer. I've had to go around with a pin and pop the bubbles and smooth them down with the edge the roller. Lots of them=big pain. Any idea what's going on here? 

Thanks in advance!


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## Bevelation (Dec 20, 2008)

You're right with the bubbling tape. There may not be enough mud and/or the mud may not be mixed down with enough water.

The fine crack along the sides of the tape is normal to an extent. You need 2 coats of filler overtop of your tape to hide that. Your second coat should also be thinner...as in not thinned down with water but thin as in more taken off when it's wet. Angle your knife or trowel steeper and put more pressure to remove more mud, so your pinholes disappear.


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## FOR THOSE ABOUT (Dec 19, 2008)

You forgot to ask for you $5.00


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## Capt-sheetrock (Dec 11, 2009)

nuge said:


> I am not a contractor--just a diy homeowner looking for a couple of solutions.
> 
> I've done a lot of taping with self-adhesive mesh tape. Seams around doors and windows eventually "pop" out so I thought I'd try paper tape. I think I've figured out why I get some larger bubbles and later peeling with paper tape--not enough JC underneath, right? One problem I haven't solved is why I get a fine, hairline crack around the edges of the tape and along that center fold line when I come back to sand and add another coat. Why is this? Sometimes it comes through additional layers of JC.
> 
> ...


are you primeing the wall, before you paint??


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## nuge (Mar 16, 2010)

Yes, I'm using primer first. The funny thing is that the tiny bubbles don't appear during the prime coat or the 1st coat of paint...

Bevelation, thanks for the tip! I'll give it a try.


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## joepro0000 (Jun 14, 2008)

Are you priming while the drywall mud is still wet?


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## nuge (Mar 16, 2010)

No, absolutely not. I wait for it to dry completely so I can sand it so it's smooth. Then I vacuum all the dust before priming.


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## Capt-sheetrock (Dec 11, 2009)

I'm coming up empty.

This may be a first for me,,,LOL


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## rhardman (Jul 7, 2009)

nuge said:


> I am not a contractor--just a diy homeowner looking for a couple of solutions.
> 
> Also, I've been skim coating to fill in dings from scraping wallpaper. I lightly sand then vacuum dust and wipe down before priming. Everything goes great during the prime and 1st coat of paint. At the 2nd coat of paint, I get tiny bubbles pushing the paint out that go back to the skim coat layer. I've had to go around with a pin and pop the bubbles and smooth them down with the edge the roller. Lots of them=big pain. Any idea what's going on here?
> 
> Thanks in advance!


Are you bubbling after the mud or is the mud pulling too?


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## nuge (Mar 16, 2010)

No, the mud doesn't pull off with the bubble. They're bubbles that only have air inside.


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## Frankawitz (Aug 13, 2008)

The problem is cause your priming first, you need to break the sealed surface, so that when you apply your mud it's moisture can penetrate into the sheetrock or plaster, by priming your mud will hold moisture on the surface, then when your last coat of paint is applied the first coat looses it's bond to the mud. Anytime you are appling mud ready mix or self setting that moisture has to be able to penetrate into the substratum.
I have done repair work for 30 years and I always sand the painted surface before I mud. if you use Durabond, easy sand,joint compound and you have humidity in the 70% and up will make primers, and paints bubble and peel, the mud surface will not dry. then when you apply the primers and paints the water in them lay on the surface of the mud, which isn't dry, and even if the primer and 1st coat of paint are dry the 2nd coat of paint will bring bubbles and sometimes peeling, I have seen sheets come off the walls before. another one is if you don't sand painted surface then you skim coat, you sand it all out, you prime it and then you apply your finish paint and the patchs pull off the ceiling and now you have these big patchs that all have to be redone.
I had a customer screw me, we had a family room 25'x 35' there was a flat roof above which was repaired. well the ceiling had taken on water for years and the owners over the years had it repaired, well it had bad stress cracks the putty coat was pulling off the scratch coat, well we used Durabond 90, paper taped all stress cracks skim coated it with topping, looked like glass. my brother said well we shouldn't have a lot of sanding:thumbup:
Next day we come back and the HO is gone to work, well we walk into the room and he cut the heat off well my tape is bubbling we had areas that were pulling off the ceiling, I called him asked WTF! he tells me he thought I was doing the job to fast and he thought it would slow down the curing if he turned the heat down:blink: some people are MORONS!
But there are a number of things that can bring bubble out.
so I would make sure you break the surface where your going to tape and mud. For a good bed coat for your paper tape I use Durabond 90 brown bags, I mix it so it's like soft serve ice cream, lay down the mud and then set your tape hold one end with 6" knife and pull it tight with your other 6" knife, then come back and lay a nice coat to cover the tape, after sets shave off any lines then use a 14" and cover with 90 again pull it tight and smooth. then finish it off with 24" knife using topping compound sand to smooth finish:thumbsup:


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## nuge (Mar 16, 2010)

Thanks, Frankawitz! Capt-sheetrock had asked if I prime before painting, not if I prime before skimcoating. In most areas, they are bare sheetrock and I do skimcoat BEFORE priming, then prime, then paint. 

However, in the areas that have the tiny bubbles, those ARE areas that were primed and painted previously and I am skimcoating over that to make it look smoother. 

This makes total sense--sand the painted areas first. Just cleaning with TSP isn't enough.

So what if there is a wall that has been painted many times before and I want to skimcoat? Sanding will break the surface but might not get through all of those layers down to the substratum. What do you do then to make sure the mud penetrates far enough?

Thanks again!!!


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## FOR THOSE ABOUT (Dec 19, 2008)

Is there a reason why you did not contract this out to a professional? Speaking for myself...this site is supposed to be for professionals to address issues, not for DIY folks who are looking for answers. Noticed you were in NJ can't believe there is any shortage of finishers there who could assist you.


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## nuge (Mar 16, 2010)

Because I like doing this kind of work.

I have tried looking for these answers on other forums for DIYers but hadn't found anything yet.

I warned everyone up front that I was not a contractor so that anyone who didn't want to read/post to a DIYer didn't have to.

Thanks to everyone who has been kind enough to take the time to read and respond. I appreciate it. Trust that I will pay it forward with similar kind favors for someone else!


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## Frankawitz (Aug 13, 2008)

We use palm sanders with 80 grit sandpaper, if you use sanding pole paper and rip them in half they fit the pad of the palm sander. I also use 36 grit for heavy oil base paints, but the paint will gum up your sandpaper. we also use wallpaper razor strippers to remove loose paint failures, this works best on plaster, drywall is to soft razors cut right into sheetrock. But we sand the areas down and then when we patch we try to stay off any paint with mud, instead we use M&H Ready Patch Spackling it can be used inside and out, and it gets hard like Durabond and it will bond with painted surfaces better. Hope that helps you out. as for helping HomeOwners without some help Man! can they screw things up sorry:whistling2:
Good luck:thumbsup:


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## Filler29 (Mar 21, 2010)

After wallpaper is removed look over the wall and if it looks like there is any adhesives from the old wallpaper left on the wall prime with an oil coverstain before skimcoat. This will eliminate any future problems.


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## cazna (Mar 28, 2010)

Those bubble holes, there is a filler product made by red devil called one time, its a very light filler thats good for filling these holes after you prime the walls, then give it a light sand and two top coats over it and usually there gone, you dont seem to need to prime it as plaster or other fillers need to. Very good time saving product, i think its american made? same as zinnser paints, good stuff too.


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## josh6106 (Nov 5, 2008)

hey nuge, frankawitz is exactly right. i mud and paint, and have had this problem before, it tends to happen more on ceilings, more heat and humidity in that area, i sand the surface prior to mudding (same reason as frankawitz) mud the area and was told by a benjamin moore rep to use a oil primer, i tend to use bin, because it dries so fast, than apply my two coats of paint. have never had bubbles again. i can remeber doing a job prior and having to paint this 1000 sq ft ceiling six times, not fun.


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## nuge (Mar 16, 2010)

Frankawitz and josh6106--do you sand the entire paint/primer layer off all the way down to the mud and sheetrock underneath? Or is just scuffing the surface enough to allow the moisture through? 

I'm doing this right now on a surface that has sort of a satin/eggshell finish so I can skimcoat it. It's a big space and I don't want to spend more time at it than is necessary. The paint/primer is coming totally off in only a few spots. The rest is scuffing nicely and I wonder if this is enough. 

Thanks again!


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## josh6106 (Nov 5, 2008)

hey nuge i only sand the spots i'm mudding and only enough to allow the new mud stick to the surface (usually 100 grit) couple scuffs is enough. i tend to do the same amount of coats over painted surfaces, as over drywall. but after you prime the mudded areas, you will see pin holes in the mud. i just put some spackle or wood filler over these pin holes (quicker than putting an extra skim coat over the area) than i put a coat of ceiling paint, only over the areas you primed. when that's dry i coat the whole ceiling . we prime with bin it's a fast drying oil primer. good luck


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## 2buckcanuck (Jul 9, 2010)

throw some mud over the area where you know there's pin hole's,wait for minute or two till you see little bubble's appear,then fire another coat over spot again and skim tight,called a double up.


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## zack 02 (Aug 27, 2010)

Sounds like not enough mudd on joint. Here lately i have had to fix some joints that were mudded to thin and you could see both sides of joint and it was cracked in the middle 2 cases. It was easier to fix then a humped joint


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