Mirror Tar + Wallpaper = Bad Stains!!

Digital ImageThe dining room wall to be papered in this Clear Lake home was originally covered in floor-to-ceiling mirrors. When the glass guys removed the mirrors, these big globs of black tar (used to adhere the mirror to the wall) were left behind. (the two black spots on the right of the photo) Oily tar like this is very bad for wallpaper, because it will bleed through the paper, creating a dark stain on the surface of the paper.

Oil-based KILZ is a wonderful product for sealing stains like this (and also blood, ink, water, rust, etc.) However, since KILZ is oil-based, and so is the tar, when the KILZ is applied to the tar, instead of sealing it, it seems to reactivate it, and mixes with it, and would allow the tar to come in contact with the wallpaper – which means a dark stain.

So to prevent this, I’ve found that, rather than try to seal off the tar, it’s best to remove it completely. So on the left of the photo, you see where I’ve taken a Stanley knife and cut out the surface of the Sheetrock, taking the icky tar with it.

Now I have Sheetrock with an torn, uneven surface, which needs to be skim-floated to smooth it out. But putting water-based joint compound on top of torn Sheetrock causes bubbles, and bubbles would show under the wallpaper. To counter that, I have applied Gardz (by Zinzer), a sort of miracle cure for torn drywall, over the torn area. Once it’s dry, moisture won’t penetrate it, and I could skim-float the wall with joint compound with no worries about bubbling.

Still, some residue of tar remains on the wall. I need the joint compound to smooth the wall, but I have found that “mud,” as we call it, also helps to seal the tar. Plus it is porous and allows the sealer to soak in, creating a better seal.

So, once the mud is dry and sanded, I am going to put Gardz on the area. Gardz is a very thin, watery sealer that will soak into the mud, hopefully sealing it. Once that is dry, I will apply a coat of oil-based KILZ. KILZ is a wonderful sealer and stain-blocker. If any stains continue to show through, I will apply more coats of KILZ, and possibly more coats of mud, as well.

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