+ Reply to Thread
Results 1 to 7 of 7

Hybrid View

  1. #1
    Join Date
    Sep 2012
    Posts
    1

    Default Cracking & Chipping Paint on Newly Plastered Walls

    I have a 100-year-old Victorian. In the front room, previous owners had patched the plaster and goughed a (what I'll call) "sort-of" texture on parts of the wall. Prefering a smooth wall surface, I got in there full with gusto, digging out the old plaster cracks down to the lathe, removing crumbling plaster, adhering loose areas back to the lathe with a glue injection technique and then scratch-coated (where applicable), brown-coated (also where applicable), and finally skim-coated the entirety walls. I applied watered down elmers at each step and a dollop of the same in each batch of plaster mix that I made (I was using powdered Dap "wall patch" plaster for all stages of the plastering). The end result was looking quite good! I was pleased with my new smooth walls...sort of shocked that it had all gone so well. And then we painted it...

    We started with a PVA-based primer as recommended by the paint store, then a nice, contractors grade paint on top. The issue arose with the first coat of paint on the walls. The ceiling and upper walls (ceiling received only a skim coat) are in one color and there wasn't any issue. The walls however, started having small bubbles pop up under the paint/primer which, when sc****d off wet, went down into the skim coat of plaster. We stopped popping/scraping the bubbles while the paint was wet, but those areas and a few others are now cracking down through that top skim coat.

    I have no idea where the fail is occurring. The plastering efforts were done over three months with at least four days of drying time after the final skim coat (so it should have been dry enough). Is it an issue with my novice application of the skim coat (a lot of that skim coat landed on old paint, about 15% on patched plaster, the bubbling is happening in both areas)? A problem with the combo of primer/paint? Contamination somewhere in the process?

    Such a HUGE effort to be thwarted at then...am wondering if anyone has suggestions about a way to fix from here...

  2. #2
    Join Date
    Jun 2009
    Posts
    271

    Default Re: Cracking & Chipping Paint on Newly Plastered Walls

    I am not a painter.
    But I am a plaster.
    I think you should have used a oil based primer.
    The DAP patching product is for patching not a full three coat plaster.
    The PH of the finished was mostlikly High and caused what is known as lime burned. The water based primer was pulled in to the plaster than it tried to exit back to the surface this caused the bubbles.
    Sand it smooth prime with oil and I think you maybe ok.
    Or maybe chech with your paint store and use something like Kils Alcohol based sealer?

  3. #3
    Join Date
    Aug 2007
    Location
    Portland, Oregon, formerly of Chicago
    Posts
    1,611

    Default Re: Cracking & Chipping Paint on Newly Plastered Walls

    I don't know what the time frame was, but most paint and primer products discourage their use before plaster has cured at least 30 days. Likewise for alkaline poured cement.

  4. #4
    Join Date
    Jun 2009
    Posts
    271

    Default Re: Cracking & Chipping Paint on Newly Plastered Walls

    Ordjen I agree that normally a 28 day cure time is recommended by with todays coating and the recommendation on the coatings products they now have what the paint manufactures claims is a HOT PRIME this can be applied over a high PH reading.I don't agree with this but this is what the paint stores will sell and state that it is Ok ?
    AS FOR THIS OWNERS PROBLEMS IT STATED THAT THERE WAS A THREE MONTH PERIOD TO COMPLETE ALL BUT THE LAST PHASE which was the skim coat.It sounds like the owner had done the home work for plaster repairs but got off track with the DAP product & Elemers Glue.Elemers Glue is a good bonding agent for the plaster edges only and deluted to be applied over the wood lath.
    Some of the problem starts with the deluted glue being applied over each phase of the work plus adding to the plaster mix.
    The ONLY thing that should be added to a plaster mix is CLEAN POTTABLE WATER.
    If you wont drink it don't use it.
    All others will effect it in some way all of which are bad.
    Placing the elemers mixture over each coat of plaster stops the water vapor transmission it acts like a very thin film of plastic between each layer. Thus driving the water back out of the plaster membrain.
    The owner could try a simple test apply a 4 inch square of oil primer to the affected wall let dry / cure. Now use a sheet of plastic say 8 inch square tape over the primed area wait say 24 hrs. see if you have moisture under the plastic around the primed area no moisture you are good to go.

  5. #5
    Join Date
    Feb 2012
    Location
    Tacoma WA
    Posts
    87

    Default Re: Cracking & Chipping Paint on Newly Plastered Walls

    A lot has been said before me, and most all of it is true. It all boils down to a moisture problem. PVA is not the primer I would have choosen. There are two types of PVA, one is a high build, used to hide drywall mudding problems. The other acts as a moisture barrier. The second is required in many areas as part of code. My guess is that the second was used before the plaster had a chance to cure and you sealed in the moisture. Scr ape what you can, skim coat with tape compound, let dry, PVA, and paint. What ever you do never use PVA on bare plaster. Good luck.

  6. #6
    Join Date
    Jun 2009
    Posts
    271

    Default Re: Cracking & Chipping Paint on Newly Plastered Walls

    Quote Originally Posted by Tacoma John View Post
    A lot has been said before me, and most all of it is true. It all boils down to a moisture problem. PVA is not the primer I would have choosen. There are two types of PVA, one is a high build, used to hide drywall mudding problems. The other acts as a moisture barrier. The second is required in many areas as part of code. My guess is that the second was used before the plaster had a chance to cure and you sealed in the moisture. Scr ape what you can, skim coat with tape compound, let dry, PVA, and paint. What ever you do never use PVA on bare plaster. Good luck.
    If you use Joint Compound to skim over a plaster wall / Ceiling
    and you are in an area that has very high humitity the joint compound will separate it self from the plaster coat.
    Keep in mind that DAP patching plaster was used this product contains Limestone ( Lime ) and Moulding plaster ( Plaster of Paris )these two compounds make up all layers of the repaired area which will take on more moisture than the older plaster that remained in place which is sand based with a lime finish.
    The note on the Joint Compound states " also for repairing cracks in interior plaster and masonry not subject to moisture. " In my area it will last for a couple of years.
    If you are in a very dry area it may work well ?

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •