Prior to prepping for wallpaper, I’ve removed a hanging shelf. It had stuck to the paint, and pulling the shelf off the wall also took some of the paint along with it.
This is a bad sign. If paint will release from the wall so easily, it’s an indicator of an unstable surface underneath, that the paint is not able to bond to.
That also bodes poorly for any coatings applied on top of it, such as my smoothing compound, primer, and wallpaper.
The most worrisome of these is wallpaper. Because unlike other substances, wallpaper expands when it gets wet with paste, and then as the paste dries, the paper shrinks a tad and puts stress / torque on the wall. If the underlying surface is unstable, these layers can actually pull apart, resulting in a ” popped ” seam.
This is not a ” loose ” seam and cannot be simply glued back together. It’s layers deep inside the wall coming apart / delaminating from each other, and virtually impossible to really repair.
So what causes this? Do a Search here to read my other posts on this topic. But causes can include incompatible surfaces, such as old oil-based paint covered with newer latex paint, gloss paint covered with new paint without proper prep / de-glossing, chalky or calcimine paint, or coatings applied to a dusty wall.
In all these cases, the top coatings won’t be able to adhere tightly, and can result in what you see here – the top layer(s) of paint pulling off the wall with just a little stress.
Even worse, in my world, is the potential of the surface beneath wallpaper seams coming away from the wall.
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