Originally Posted by Over-Head
Ok, so you descided to "seal it" then mud it, with some kind of paint...(sorry, but about the WORST thing you could have done), and now it’s bubbling through.
WHY??
Well, it’s really rather simple, when you understand that a sheet of Gyproc is made from a composit calcium compound surounded on BOTH sides by TWO sheets of paper. The first being the "bonding "page"", the second being the top face sheet, which is made with 70% glue to try and STOP moisture saturation.
This is also why they created "Blue Board" for bathrooms.
See it’s a a weird relationship between drywall and paint....They realy dsont like each other. Thats why PRIMER is such a fast drying product, it drys so fast it doesnt have a chance to soak all the way through, BUT creates a "water proof" seal for the finish coat to be applied.
. Think about what happens when you spill water on paper??? Thats exactly what your doing when you "paint" drywall.
The pic’s your showing, show that the "water barrier" coat of paper has been ripped off, what’s left is the "bonding" paper which holds the gypsum retain it’s shape in a "sheet" form.
By Painting it with ANY kind of paint what you did was allow small amounts to seep between the TWO layers of paper surrounding the torn area...thus resulting in loosening the adhesion of the double layer of paper.
Now add to this the fact that ANY home regardless of how well you clean it, will have air born particles, these particles, IE: animal hair, cooking oders, hair car products, smoke (not just ciggs, but cooking) etc, etc, etc, land on painted surfaces, and create a berrier which DOESNT like paintor mud products.
The exposed paper would have had a better adhesion than ANY paint you could have put on top of it.
BUT...Since you did take the advice of others and "paint/prime" it...you’ve lost some of that adhesion, not to mention compounded the problem. As mud and paint although will adhere together, really don’t like to "dance".
At this point, what you need to do is...
Cut out the effected area, if possible, (but not really super important)...try not to go all the way through to the gypsum.
If ya do no biggie...
Hit it with any kind of quick set "mud" compound, and wipe it tight to the surface.
If you don’t think you’re able to mix this up,,,then just go with a commercial brand of per mixed drywall mud., let it sit over night.
Lightly sand, then hit it again, you want to add aprox: a 32nd of an inch
thick coat, let it sit until dry.....lightly sand,
hit it a 3rd time...finish sand
then SEAL it with a product like Benjamin Moor’s "Fresh Start" which is a water damage/Stain sealer...this will NATURALIZE these aforementioned air born oils and particles which don’t like plaster or paint.
Once that primer is dry...finish with what ever top coat you choose.
Your welcome.
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