# But joint mesh pops in primer



## Nailbags (Feb 1, 2012)

The mesh tape!


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## joecaption (Nov 30, 2011)

It should have been paper not mesh tape.
That drywall compound seam should be about 12" wide.


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## Nailbags (Feb 1, 2012)

To be more specific I have seen the mesh tape do what your describing many times in a lot of homes I have done remodel work in. Always use paper tape!


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## sxotty (Mar 25, 2013)

Are you suggesting that mesh tape is always the worse choice, or that paper is just better on but joints (but not on tapered), or paper is always better? Just curious. I asked a drywall guy and he said he used mesh and did not really think it mattered much, but I have personally been thinking paper tape may be the better choice in these situations. At this point I will probably just paint again and see if a person can notice. In the future though I will definitively be using paper tape. I used it in some places in other rooms and the results have generally been better, but it was more finicky.


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## joecaption (Nov 30, 2011)

I've been messing with houses for over 40 years and have never once seen a pro finisher use mesh tape.


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## coupe (Nov 25, 2011)

I agree with those above, should've been paper tape. most always, tape hairline cracks begin at bedding. sticky stuff isn't bedded, if not perfect? any adjustment sticky is gone. when coated, as mud dries and shrinks it pulls the mesh lose, sticking to mud. no way to get back under it! same with paper tape, trying to get perfect might pull all mud from under tape, coating mud will pull tape loose= hairline crack. once it's loose, it's loose no way to get sticky back. just a tiny bit of dust under mesh, no sticky coating over and over gets nothing under. if pull it loose to get under? when smoothing, the air has to go somewhere bubble. once air gets under can't get it out just move it around!

good luck


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## ToolSeeker (Sep 19, 2012)

Maybe just coincidence you decide. Most of what I do now is repair, in the last 2 weeks I have been to 2 homes with a total of 7 cracks. The things they had in common 
all vertical cracks
all done in the last 3 years
all done with mesh tape.
done by different people.
Why I don't use mesh tape, is thicker than paper so takes more mud, whice makes it very easy to leave a hump. Since it is thicker it is very easy to sand to much mud off it, then you have those lovely squares to deal with. It has no strength vertically so cracks at the slightest movement. In my opinion mesh tape should be on the same shelf as all in one paint.


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## Nailbags (Feb 1, 2012)

yep the cost of mesh tape in the store is high and the cost of fixing the problems are even higher.


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## PoleCat (Sep 2, 2009)

I stepped on the same land mine. I see the consensus is quite clearly that the mesh is the culprit. Did not see any advice for correcting the issue however. Should this joint be excavated to the board or is there a less painful solution?


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## ToolSeeker (Sep 19, 2012)

What I would try is another coat of mud and feather it out farther on both sides of the seam. Probably at least twice as much as it is now and be careful not to sand to hard.


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## Nailbags (Feb 1, 2012)

ToolSeeker said:


> What I would try is another coat of mud and feather it out farther on both sides of the seam. Probably at least twice as much as it is now and be careful not to sand to hard.


Yeah the problem then is you have a high ridge build up. some of the things I have had to do was 1 cut the tape out redo with paper and sand etc.. at least this happened before any texture and real paint was used. a good skim coat will help as well. and that is another reason why I won't do vertical drywall. the house settles and pop goes the seam long after the contractors are gone.


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## Gary in WA (Mar 11, 2009)

"Are you suggesting that mesh tape is always the worse choice, or that paper is just better on but joints (but not on tapered), or paper is always better? Just curious."------------------------------ Mesh tape stretches to show a crack, paper tape doesn't;
_
"In the case of paper tape, approximately 30 lb./lin. in. of tensile force (pulling apart) is required to break the
tape with no measurable movement or elongation (no stretching). On the other hand, glass-fiber tape elongates
(stretches like a rubber band) 0.03" before reaching maximum or breaking load of 70 lb./lin. in.
Research investigation has shown that hairline cracks or nail pops are visible at 0.01" of movement with
veneer plaster system joints treated with glass-fiber tape. Actual load at that amount of movement is only
20 lb./lin. in. or about 30% less than the breaking load of paper tape (with no movement). As such, paper tape
provides greater joint strength and is recommended where greater movement and shrinkage is anticipated.
The performance of glass-fiber tape is somewhat improved if the tape is prestressed or stretched slightly during
its application and imbedment with the veneer plaster. The prestressing is accomplished with the presetting
because as the veneer plaster sets, it expands and furnishes the movement necessary to stretch or prestress
the tape, thus increasing its immediate resistance to load (tensile forces). The amount of expansion provided by
the plaster is dependent on the rate at which the plaster sets. With rapid-drying conditions (see graph), the
plaster expansion will be significantly reduced resulting in no tension (prestressing) in the glass-fiber tape,
thus reducing its ability to control cracking.
Paper Tape Application Techniques The Sheetrock joint tape and Durabond or Easy Sand joint compound method is unaffected by rapiddrying
conditions and achieves maximum joint strength (about 30 lb.) when dried. The setting-type compound
is recommended, because once it is set, it remains stable, even when troweling the wet coat of veneer plaster
over it. If a drying type of joint compound were used, it would be rewetted by the plaster application causing
movement of the tape resulting in distortion of the finish surface and possible loss of joint strength."_ From: http://www.usg.com/rc/technical-art...laster-joint-reinforcement-systems-en-PM5.pdf Granted, that was plastering but still applies. Notice as it re-wets with additional coats/texture, it can then crack anew. 

So you were doomed from the get-go with the mesh tape and a second (possible) doom; if you used sistered lumber that was new (rather than old)- MC of 19% that will dry to 10% and crack then; pp. 11, 12; Another reason to use the shortest required fastener, rather than a longer one. 
https://docs.google.com/viewer?a=v&...Foimib&sig=AHIEtbQYAZ0SWjnVJNXhfHFsk1RrK9G2HQ

Fastening it off is similar to laying sub-flooring;
_"5.6.1 Starting at the center of the gypsum panel product, the
first set of nails, shown by solid dots, shall be applied in row
1 first, then in rows 2 and 2A, then in rows 3 and 3A, then in
rows 4 and 4A, etc. Nailing shall always proceed from the
center to the ends and edges of the gypsum panel product."_ From, and any other questions unanswered, lol; http://www.lafargenorthamerica.com/GA-216-07 English.pdf

The third doom (possibly); using a "drying" compound rather than the required "setting" compound for the mesh tape embedding; 
_"Drying Versus Setting
Drying-type compounds, which contain water, must be allowed to dry completely in order to ensure creation
of a strong joint. The time needed for thorough drying may not be available in an assembly-line environment. If finished sections are moved before joints have dried completely, cracking may result. Drying type compounds are available in both powder and ready-mixed forms. They can only be used with paper tape.

Setting-type compounds harden chemically for quicker finishing and joint strength, and are available in a variety of setting times. This makes them especially suited to assembly line production. They can be used with both paper and fiberglass joint
tape." _From: http://www.usg.com/rc/installation-...s/manufactured-housing-handbook-en-MH1216.pdf

Gary


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## Sir MixAlot (Apr 4, 2008)

Most drywall mesh tapes clearly state on the packaging "setting type compound only". :thumbsup:


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## sxotty (Mar 25, 2013)

ToolSeeker said:


> What I would try is another coat of mud and feather it out farther on both sides of the seam. Probably at least twice as much as it is now and be careful not to sand to hard.


 Ok so I ended up just doing this. I primed and there was no more of whatever the heck that was. I painted later in the day and after that I could still kind of see something there, but it looks more like a hint of the seam (no crack) and it might fade with a second coat of paint or time. Might just be the result of changes in how much absorbed. Anyway I am happy enough with the result. I will definitely keep the issues with mesh tape in mind. I actually had some good luck in the past with mesh tape. I had a crazy corner (45 on the ceiling) that I probably did all wrong in my first room b/c I could not figure out how to attach two sheets well the the roofing member that was not modern dimensional lumber (all wavy and stuff). I ended up with a strip of metal screwed in to hold the drywall down then built the corner way up with layers of mesh tape. It has held up well and looks nice, very crazy though.


Gary in WA said:


> The performance of glass-fiber tape is somewhat improved if the tape is prestressed or stretched slightly during
> its application and imbedment with the veneer plaster. The prestressing is accomplished with the presetting
> because as the veneer plaster sets, it expands and furnishes the movement necessary to stretch or prestress
> the tape, thus increasing its immediate resistance to load (tensile forces). The amount of expansion provided by
> ...


 Thanks for all that. The guy I talked to did use setting type compound with mesh tape, and I did use drying type compound... oops. Anyway things are ok except for that one seam in that and the other rooms, so I will just take my good luck and be happy.


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## PoleCat (Sep 2, 2009)

ToolSeeker said:


> What I would try is another coat of mud and feather it out farther on both sides of the seam. Probably at least twice as much as it is now and be careful not to sand to hard.


I did this after priming the joint with Kilz. It reappeared as it dried. These cracks are in a butt joint on the ceiling by the way. Another area I just put about 4 coats of Kilz on and at the moment it is all but invisible but it is like a ticking time bomb probably.


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