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Thread: drywall seams showing through primer

  1. #1
    DIY Member econguy's Avatar
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    Default drywall seams showing through primer

    Hello

    Several months ago, I drywalled, taped, mudded, and primed a couple of bedrooms. They looked fine until the last few weeks. All of a sudden, I can see a lot of the seams, both tapered and butted, through the primer. The tape itself isn't peeling or blistering, and the drywall itself isn't loose. Rather, it's one of two scenarios...I can either see the crease (and only the crease) along the length of the tape, or the crease has become slightly recessed, forming a very shallow, narrow valley (I think it depends on which way the crease was facing when I first laid the tape). Some - but not all - of these seams have a hairline crack along part of their length.

    Can I just add a thin layer of setting-type joint compound for either case? Or do I need to add a layer of tape, and then the 2-3 coats to feather it out? If so, can I add the tape on top of the primer, or do I need to tear out the existing tape and sand the area down?

    Thanks for any advice
    Will

  2. #2

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    Might be the perfect application for a product called Sheetrock Tuff Hide primer surfacer by USG

    This stuff supposedly will hide creases and hairline cracks, while priming the sheetrock at the same time.
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    Jack of all trades frenchie's Avatar
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    Sounds like shrinkage. Wasn't left to dry long enough before priming, or it was mixed a little wet...

    If the tape's still solid, there's no reason to replace it.

    Skimcoat over, prime, paint.




    There's never a reason to tape over tape.
    Last edited by frenchie; 12-06-2007 at 08:03 PM.
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    DIY Member econguy's Avatar
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    Hi VerdeBoy - thanks for the suggestion, but for now I'm going to stick with a regular primer I can roll on. The Tuff Hide requires a sprayer.

    Frenchie - I used USG Easy Sand 45, and I primed after a couple of hours. Was this too soon? The compound had turned from grey to white, and I was able to sand it, but I've since read that I should have let it dry for 24 hours. I was under the impression that a setting-type compound didn't require that much time, and the "45" referred to drying time (when in fact it's setting time, and there can still be a lot of moisture). If it matters, I primed with Zinsser Bullseye 1-2-3., which is advertised a "breathable". I planned on painting tomorrow, which would have given about 1.5 days since priming....if I don't see any blisters, should I go ahead?

    Thanks again for the help
    Will

  5. #5
    Jack of all trades frenchie's Avatar
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    Yeah, it was too soon. On the plus side, you won't get shrinkage from setting-type, because it is set. On the minus side, it probably wasn't dry, so you might get some peeling or cracking in the primer or paint, eventually...

    No blisters is a good sign, you're probably okay. Good call to give it an extra day between prime & paint.


    On a different note - I'd prime again, at least once, before painting. You've got part of a wall with much less primer/paint on it than the rest of the wall; it'll absorb paint a bit differently, giving your top coat a slightly different texture over the new plaster.

    When I want a repair to absolutely not show up, I spot-prime the repair twice, then prime the whole wall, then paint.
    Master Plumber Mark:

    there is nothing better than the
    manly smell of WD 40 in the air
    while banging away on brass with a chisel and hammer...

    it smells like......victory......

    do not hit your thumb...
    __________________
    Just so everyone's clear: I'm the POODLE in the picture ("french", get it?) The hot woman is my wife.

  6. #6

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    Quote Originally Posted by econguy View Post
    I used USG Easy Sand 45, and I primed after a couple of hours. Was this too soon? Thanks again for the help
    The Easy Sand is great for putting on multiple coats in one day and essentially finishing a large drywall repair that would otherwise take several days to finish. But as you figured out, you still have to let it dry for a day or more before priming/painting.

  7. #7
    Forum Admin, Expert Plumber Terry's Avatar
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    When I was building houses, we would spray on the PVA undercoat before we sprayed on the texture.

    Then when the texture was added, it adhered to the walls and ceiling evenly.

  8. #8
    DIY Member econguy's Avatar
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    An update....

    Went to go paint today, and no blisters on the primer. Seemed like a good thing. I had a roll of blue painter's tape lying around, so I ripped off a strip, placed it against the area I mudded and primed, and pulled. Big strip of primer came off. Put a putty knife underneath, and was able to work off pretty big areas of primer, biggest was maybe 4"x6" . So I spent the day scraping off what I put on a couple of days ago. I won't be able to work on it again til next weekend, so that should be plenty of time for it to dry.

    Lesson learned...let the joint compound dry . Ironic though, cause I was actually debating whether to prime when I did (it was the end of a long day and I was tired), or wait until the weekend. I figured I'd get a jump on the painting prep, so I decided to prime. Shoulda listed to my "lazy" voice and waited.
    Will

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    Forum Admin, Expert Plumber Terry's Avatar
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    Wet mud?

    I found that you have to leave a few windows open for the wet air to escape.

    We would remove the thermostat, and just wire nut the two wires together. I would leave it that way for a month.

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    DIY Senior Member construct30's Avatar
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    In wet cold weather I like to use a dehumidifier on the job. I quit using paper tape too. I like the fiberglass, never have a problem with it. It requires a little sanding after the first or second coat, but it dries easier under it and doesn't come loose if you coat too fast or if it dries too quick. You have to get the joint compound dry though.

    Good primer is your best friend when it comes to new drywall. Some brands will never stick if you buy from the box stores. Use a good pro brand of primer from a paint store ask around in your area. You will pay three to four times as much, but how many times do you want to do it.

  11. #11
    Jack of all trades frenchie's Avatar
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    Quote Originally Posted by construct30 View Post
    In wet cold weather I like to use a dehumidifier on the job. I quit using paper tape too. I like the fiberglass, never have a problem with it. It requires a little sanding after the first or second coat, but it dries easier under it and doesn't come loose if you coat too fast or if it dries too quick. You have to get the joint compound dry though.
    Fiberglass cracks a lot more easily than paper. Anyone who's demoed both, knows; and even USG says it's only about 1/3 the strength.

    Good primer is your best friend when it comes to new drywall. Some brands will never stick if you buy from the box stores. Use a good pro brand of primer from a paint store ask around in your area. You will pay three to four times as much, but how many times do you want to do it.
    Truer words have never been spoken. About paint, in general.

    3-4 coats of cheap paint, still doesn't look as good as 1-2 coats of BM.
    Last edited by frenchie; 12-09-2007 at 11:30 PM.
    Master Plumber Mark:

    there is nothing better than the
    manly smell of WD 40 in the air
    while banging away on brass with a chisel and hammer...

    it smells like......victory......

    do not hit your thumb...
    __________________
    Just so everyone's clear: I'm the POODLE in the picture ("french", get it?) The hot woman is my wife.

  12. #12

    Default drywall seams

    If you take your fingernail and tap on the tape joint you shoud hear a difference. It will sound hollow right in the middle. Take a utility knife and v out the hollow part. This is usually about a 1/2 inch wide. Put mesh tape down the length of the seam. I like to use 5 minute quick set mud. If you feel more comfortable use 45 or 90 minute. Use a 10" knife and mud over the mesh tape. Make sure you pull the edges tight. after about 5 minutes, the 5 minute mud begins to act like clay. Take your knife and run it down the seam smoothing out the bump that will be there where you created your v. If you use 45 or 90 minute you may have to wait longer for the mud to work like clay. You want to use as little mud a possible but cover the mesh completely. Once dry use a finishing mud over the top. Use the 10" knife and make it about 18" wide ie. run your 10 knife down each side of the tape joint.

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