# mud shrank after priming/cause?/ fix?



## all pro siler (Feb 22, 2012)

i just hung and finished a new construction home. set tape with e-z sand 90 and did mid weight for top coat. set all feather seams with paper tape and all inside corners with straight flex and meatal outside corners. did 3 coats and sand then tuch up coat. used a light on all joints. muded the same way i have many time look realy good. when i primed the mud shrank up and all joints and screws have now showed up. there was more than enough time between coats to dry. i have done this many time with no problems but something is off need help. has any one ever heard of this happening and how do i stop it and fix this?


----------



## moore (Dec 2, 2010)

all pro siler said:


> i just hung and finished a new construction home. set tape with e-z sand 90 and did mid weight for top coat. set all feather seams with paper tape and all inside corners with straight flex and meatal outside corners. did 3 coats and sand then tuch up coat. used a light on all joints. muded the same way i have many time look realy good. when i primed the mud shrank up and all joints and screws have now showed up. there was more than enough time between coats to dry. i have done this many time with no problems but something is off need help. has any one ever heard of this happening and how do i stop it and fix this?


Wet rock dried out. Then shrunk..


----------



## all pro siler (Feb 22, 2012)

was in a 65 degree house for 2 week before hung and it looked good when it got there. was on the walls of about a week before we got to the mud.


----------



## mudslingr (Jul 18, 2010)

I agree with moore. If the board isn't dry or climatized it will do funky things. Is it very cold where you are or maybe very humid ? Either way, wet drywall sucks until dry. Even then... !

And then you re-wet the mud with primer causing it to shrink even more !


----------



## mudslingr (Jul 18, 2010)

all pro siler said:


> was in a 65 degree house for 2 week before hung and it looked good when it got there. was on the walls of about a week before we got to the mud.


Do you know for a fact that it was 65° for 2 weeks previous or just the day you got there ?


----------



## all pro siler (Feb 22, 2012)

for a fact that is was 2 weeks... wating for a payment before we hung the board.


----------



## mudslingr (Jul 18, 2010)

Tough to say.
I get that happening once in awhile when I get board from a place that stores it outside in crappy sheds. When you cut it and try to snap it, forget it ! More or less have to fold it and it isn't easy on 5/8. :no: 

But if I let it sit for a few days in scattered piles in a WARM environment that usually solves the problem.


----------



## nu-wall (Feb 11, 2012)

Do you have permanent or temporary heat? Was there an unusual amount of humidity when priming and / or texturing? (Did you apply texture?) What kind of air circulation did you have during the drying stages? Were windows closed or open for drying? Did humidity have an escape route? Did the walls have visquine vapor barrier installed over the insulation? How fast did the primer and/or texture and/or paint dry? All of these - when the answer is righ (or wrong) can contribute to causing joints and screws that were in good shape to show up later. Rock will swell from sucking up a lot of moisture that had no escape route. This can cause joints to show (remember, there's factory-applied hardener along all the recess joints and this will not suck up as much moisture nor swell as much - the JOINTS). If the rock swells it will also hollow out the dimple where the screw was set and had the proper number of coats. I have seen this a number of times over the years. Most of the time over a weekend during the warmer months when we were relying on natural drying but plenty of times also when the job is closed up and using temporary or non-circulating type heat. Most commonly when this occurs it will not 'correct' itself; that is to say you can't just dry out the humidity in the board and expect the problem to go away. You'll have to fix the problems just like a bad job (unfortunately, that's what the job has become).


----------



## JustMe (Apr 17, 2009)

all pro siler said:


> i just hung and finished a new construction home. set tape with e-z sand 90 and did mid weight for top coat. set all feather seams with paper tape and all inside corners with straight flex and meatal outside corners. did 3 coats and sand then tuch up coat. used a light on all joints. muded the same way i have many time look realy good. when i primed the mud shrank up and all joints and screws have now showed up. there was more than enough time between coats to dry. i have done this many time with no problems but something is off need help. has any one ever heard of this happening and how do i stop it and fix this?


Did the mud shrink? A theory:

The board was wet, expanded, and then dried. But the board's paper developed an 'expansion memory' enough so that when it was hit with wet again, it allowed the paper to quickly swell - the mudded areas didn't expand, but the areas around the mud expanded. The primer dried while the board paper was still expanded, so the look of the mud having dried back was given.

Regardless if the theory is right or not, anytime we've run into such a problem, it seemed moisture was a factor. One of the worst was when some wood sheeting that had been put behind the board got wet - propane heaters were being used inside a very large building, which created moisture problems. As the wood sheeting kept drying and shrinking, it also kept the drywall from drying out well. I wasn't on that job at the time that happened, but heard about it. Took a few tries to get things looking well enough - semi-gloss paint used as well.

On another job, the painter sealed a large room and then went a bit crazy with the amount of paint. Lots of humidity in there, and things were showing in places because in part I knew where to look. Luckily, it was all painted white, was a boiler room, and they were in a rush for it. So it passed.

As for a fix, the only way we were able to make screws 'disappear' on another job was to put a bit of a wide, thinnish coat over each one with a 6" knife and then sand them, but not all the way back. We found that just filling screw spots tight, as you normally would when spotting screws, wouldn't work. It still looked like they were shrunk back a bit. Part of the problem on that job could've been the moisture coming out of the concrete floor. We tried a couple different types of mud and a couple different types of primer on that job. None of that helped. Problems still kept showing up in places.


----------



## cazna (Mar 28, 2010)

Fans and dehumidifers, A little heat, and ventilation, Its all our best friend, The dehumid is very important.


----------



## Stopper (Nov 5, 2011)

*How soon after priming did the problem show up? 

*The house IS insulated isn't it?

*Whats the outdoor temp there?

*Do the internal walls have the same problem as external walls that back 
onto outside walls? etc? 

*What about the ceiling? steel batons? same problem?


----------



## all pro siler (Feb 22, 2012)

thanks too all that have posted with thier experience with the problem. many have ask a few questions about heat, temp, and ventilation. the heat was a perment 90% furnace that was pulling moister out when runing (of couse), and working well too. it did not have moister barriar, becuse it had spray foam about 1" all the way around the house (exepct the ceilling) then batt insalation on top of that. the out side temp has been about 40 and the inside 65-68. we did have a fan running just to move a little more air. The walls are not as bad as the ceilling, interior or exterior. the problem was apparent as soon as the primer was drying. We have been fighting the problem and the only thing that we have been able to do was prime it all and go back with 90 and put more on, sanding it light leaving it alittle hight and touch up the primer. still don't know were the mostiure came from or if there was any? but it has been the worst finish job i've ever done. thanks again to all!


----------



## fr8train (Jan 20, 2008)

A Few questions:


What brand primer did you use?
Did you burn/fuzz up the paper around your joints?
How many coats of primer?
Did you sand in between the primer coats?


Sounds like a classic case of joint flashing to me.


----------



## all pro siler (Feb 22, 2012)

sherwin william pro mar 200, there was a coulpe of spots that did get fuzzed not to bad, it was around the srews though. Did sand between coats (light) just to nock off any fuzz and contaminates. there was 2 coats of tinted primer.


----------



## fr8train (Jan 20, 2008)

Well then, I'm at a loss, I'll leave it to the more experienced folks from here on out! good luck


----------



## PrecisionTaping (Feb 2, 2012)

I think pretty well everythings been said!
Goodluck man!


----------



## nu-wall (Feb 11, 2012)

The only possiblity left that I can think of is the furnace having been shut down by another party and even that would seem to me to need to have been done right after priming while it was still wet.....
There simply are no possiblities that come to my mind....
Hope things end up good.


----------



## moore (Dec 2, 2010)

nu-wall said:


> The only possiblity left that I can think of is the furnace having been shut down by another party and even that would seem to me to need to have been done right after priming while it was still wet.....
> There simply are no possiblities that come to my mind....
> Hope things end up good.


 wet mud on top of wet mud. Nothing had a chance to completly cure between coats. just because it turns white don't mean it's dry.


----------



## mudslingr (Jul 18, 2010)

moore said:


> just because it turns white don't mean it's dry.


:thumbup: And that's pretty hard to get into some tapers' skulls.

She looked horny. Boy was I wrong !:blink:


----------



## AtlanticDrywall (Mar 5, 2012)

Interesting situation. I doubt that the joint shrunk because of the application of the primer. As someone else mentioned, it could be the simple cause of the screws and seams flashing. Four questions I would have knowing Sherwin Williams products pretty well:

A. Did you use a power sander?
B. How did you prep the rock before spraying it?
C. Did you back roll the primer or just squirt it with two coats? 
D. Have you put a staight edge or a one of your larger knifes against the seams to make sure shrinkage is what is causing them to show? 

Sherwin Williams makes a decent product. However, if you're sanding with a power sander you're going to chafe the board whether you're a great power sander or not. Thus, if you're using a Sherwin Williams product it's very important to prep the board properly if you don't plan on back rolling. If you don't, what you will be left with is a surface that shows ever screw and seam. It's not that the taping work is bad, it's that the paint isn't hiding the roughness of the areas that the sander went over. 

Just my .02.


----------



## drywallninja (Apr 28, 2013)

*Mud shrinking.....*



all pro siler said:


> i just hung and finished a new construction home. set tape with e-z sand 90 and did mid weight for top coat. set all feather seams with paper tape and all inside corners with straight flex and meatal outside corners. did 3 coats and sand then tuch up coat. used a light on all joints. muded the same way i have many time look realy good. when i primed the mud shrank up and all joints and screws have now showed up. there was more than enough time between coats to dry. i have done this many time with no problems but something is off need help. has any one ever heard of this happening and how do i stop it and fix this?


What kind of board was hung? Was is lightweight or the good old stuff?


----------



## Trim-Tex (May 4, 2011)

All Pro, Here is my 3 cents

If the gypsum board is too wet and then dries out after finishing and painting your screw heads would stick out slightly ( not the case here).

I'm thinking your first primer coat was to heavy and shrunk back your mid weight mud. All MUDs are not the same, a bucket of heavy wt. mud can weigh 15 lbs more than a bucket of all purpose light wt. most of that difference is water, more water = more shrink and it takes longer to dry.

Our in house Pro uses light wt. All Purpose joint compound (low shrinkage formula) on his first coat with Mud Max (white glue) and then finishes with the same compound with no glue. Using the same compound on all 3 coats gives him the ultimate bond 3 times and shrinks the least. Yes it is a little softer than other MUDs but is the least brittle and it works for us. ( remember every one can do it different and MUDs change from region to region.)

More recommendations: 
Buy a moisture meter, temperature & humidity gauge, box fans to exhaust at windows. 2-4 dehumidifiers and a 12 pack of light beer. 

Check moisture content of framed house with meter 2weeks before stocking drywall if levels are too high take action and get ( GC or Builder) it dried out. When your dealer is stocking the job site with gypsum board have them spread it out to more areas with smaller stacks. Immediately get your dehumidifiers running and fans blowing across the board. 

I have a meeting and I'll add more later

Joe


----------



## moore (Dec 2, 2010)

Trim-Tex said:


> 2-4 dehumidifiers and a 12 pack of light beer.
> 
> 
> 
> Joe


----------



## boco (Oct 29, 2010)

Thats some good advice from Joe. Another thing that can help is when spray priming spray all ceilings first. As you spray make sure to place fans in the rooms. Once ceilings are dry then go ahead and shoot the walls. By doing rooms in steps and adding fans as you go it helps the primer dry faster which helps with the amount moisture you are adding to house. Normally I dont run heat or dehumids while spraying but fans are cheap and having plenty of them is a must. Also having a window open is another way to get out the moisture. The average house takes 25 gal of primer thats a lot of moisture. Spray it on at the right thickness give it a good backroll. Next fire up dehumids and electric heaters and get it dry as fast as you can. Wait till the next day before top coating. .


----------



## Trim-Tex (May 4, 2011)

Part 2

Applying primer-sealer to Vinyl beads,

Vinyl beads don't need to be primed or sealed. The exposed part of our beads will soak up 0% of what you spray or roll on. All of our beads have a very paint ready etched surface. IT IS BEST FOR YOU TO APPLY FINAL WALL COLOR TO THE EXPOSED VINYL

Most people put way to much primer-sealer on/near the corners and its easy to do. If you spray/roll left, right and middle, now you have loaded up the mud right at the corner bead. Too wet application could cause a touch of shrinkage to your mud in that area. 

When spraying primer do the center only (medium coat) and then stay away on the right/left. OR go light coat right and left and then DO NOT spray the center. Go ahead and do a light pressure back roll if you want.

When rolling primer on or near corners, go easy and apply a medium coat. It is OK to roll/clean up the nose of the bead, do that when your roller is the least loaded.

Have a great day!
Joe


----------



## thefinisher (Sep 2, 2011)

We have had problems with the lighter mid weight muds shrinking back about a month after the job is finished (when they turn the heat/ac on). We switched to the heaviest A/P we can get which around here is RUCO. Havent had a problem with it yet. To me the lighter weight muds don't have the added glue strength and since they don't have as much water in them, they tend to soak up more water than a heavy AP with a ton of glue. The light mud is light because of the lack of vinyl glue in it. Vinyl is very water resistant.... That is my theory and it is proving to work well so far.


----------



## Mudslinger (Mar 16, 2008)

thefinisher said:


> We have had problems with the lighter mid weight muds shrinking back about a month after the job is finished (when they turn the heat/ac on). We switched to the heaviest A/P we can get which around here is RUCO. Havent had a problem with it yet. To me the lighter weight muds don't have the added glue strength and since they don't have as much water in them, they tend to soak up more water than a heavy AP with a ton of glue. The light mud is light because of the lack of vinyl glue in it. Vinyl is very water resistant.... That is my theory and it is proving to work well so far.


The perlite makes light mud light. http://www.perlite.org/members/members-pages/USGCorp.html


----------

