Peeling Paint = Potential Problems

Here before hanging wallpaper, I have removed the light fixture over the bathroom vanity .  Some of the wall paint was stuck to the base of the light fixture, so was torn away from the wall when the fixture pulled away.  In the photo, the cream colored area is the current semi-gloss paint , and the greyish area is the paint that is beneath it. 
Problem is, wall coatings surfaces should adhere to each other.  In other words, the cream colored paint should not have peeled away from the grey paint under it.
Usually this happens because proper prep was not done before the new layer of paint was applied.  Surface coatings (meaning paint or wallpaper ) won’t stick to glossy surfaces, nor to dusty surfaces.  So, if you’re painting over gloss paint, first a deglosser needs to be used, or a bonding primer .  A good paint store guy ( Sherwin-Williams ) can advise you.  If the original surface has dust , as from sanding or construction , this needs to be wiped off with a damp sponge , and that has to be rinsed clean frequently.  Often a primer should follow that.  Again, consult a knowledgeable paint guy.
All of this is not so desperately important if you’re going to apply paint.  Even on an unstable surface , paint simply dries and sits there.  It only peels away if tension or pressure is put on it, such as removing the light fixture in the photo above.
But wallpaper is different.  Because wallpaper shrinks when the paste dries , tension is put on the seams .  If the surface below is unstable , this tension can cause the surfaces below to come apart / delaminate .  This can result in seams that pull away from the wall.
This is not the wallpaper pulling away .  This is the layers underneath that have actually come apart from each other.
And it usually cannot simply be ‘ glued back down .’ 
You can do a search here to read previous blog posts about this issue.  

Tags: bonding primer, coatings, come apart, construction, deglosser, delaminate, dries, dust, dusty, glossy, glued back down, light fixture, paint, paste, peeled away, prep, pressure, primer, pulling away, sanding, seams, semi-gloss, sherwin-williams, shrinks, surface, surface coatings, surfaces, tension, unstable, unstable surface, wallpaper