My 40 plus years in the painting, drywall and all kinds of challenging home
repairs have always led to solutions that may not appear on a product label.
Painting over a wallpapered surface can be a successful project. Removing
wallpaper can be a messy task and can create more work than necessary. My
process that works is: I inspect the wallpaper for any loose seams or bubbles.
I remove the edges by tearing off the loose edges until the area comes to a
sound area. I cut out the bubbles with a razor knife being careful to just
remove the bubbled areas. The next step is to prime the entire wallpapered
surface with an oil base primer. I have used some water based primers with
success it I always test them first to see if the wallpaper or teared off
areas cause the paper to loosen or bubble. Kilz 3 is one of late that I have
used with success after testing. After the primers has thoroughly dried I
apply joint compound over the vertical seams and areas where the loose seams
and bubbles were removed I start with a 6 inch broad knife on the first coat.
Let dry. I skim the second coat of compound with a 8 or 10 inch and fish with
a 14 inch kinfe on the final coat. I do not sand between coats, only scraping
lightly with a broad knife to remove any raise edges. After I am pleased with
the compound being smooth I sand lightly or use a very damp cloth wrapped
around a sanding sponge block to eliminate drywall dust. The damp cloth and
sanding block is a little tricky but once you get results without all the dust
it's worth it. Once all the area are dry and smooth I like to prime the wall
with a best quality drywall primer and follow up with my finish coat of first
quality. Sounds like a lot of steps but each one goes quickly and eliminates
the big mess of removing wallpaper and repairing gouged out places that
scrapers have made. An additional step that I do is that I caulk the perimeter
edges and corners with a good siliconized latex caulk or use a product called
Grab made by Loctite. This is my Tested Tried & True method of painting over
wallpaper.

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On Sun, 8 Dec 2019 01:14:02 +0000, Tested Tried &True
m wrote:

My 40 plus years in the painting, drywall and all kinds of challenging home
repairs have always led to solutions that may not appear on a product label.
Painting over a wallpapered surface can be a successful project. Removing
wallpaper can be a messy task and can create more work than necessary. My
process that works is: I inspect the wallpaper for any loose seams or bubbles.
I remove the edges by tearing off the loose edges until the area comes to a
sound area. I cut out the bubbles with a razor knife being careful to just
remove the bubbled areas. The next step is to prime the entire wallpapered
surface with an oil base primer. I have used some water based primers with
success it I always test them first to see if the wallpaper or teared off
areas cause the paper to loosen or bubble. Kilz 3 is one of late that I have
used with success after testing. After the primers has thoroughly dried I
apply joint compound over the vertical seams and areas where the loose seams
and bubbles were removed I start with a 6 inch broad knife on the first coat.
Let dry. I skim the second coat of compound with a 8 or 10 inch and fish with
a 14 inch kinfe on the final coat. I do not sand between coats, only scraping
lightly with a broad knife to remove any raise edges. After I am pleased with
the compound being smooth I sand lightly or use a very damp cloth wrapped
around a sanding sponge block to eliminate drywall dust. The damp cloth and
sanding block is a little tricky but once you get results without all the dust
it's worth it. Once all the area are dry and smooth I like to prime the wall
with a best quality drywall primer and follow up with my finish coat of first
quality. Sounds like a lot of steps but each one goes quickly and eliminates
the big mess of removing wallpaper and repairing gouged out places that
scrapers have made. An additional step that I do is that I caulk the perimeter
edges and corners with a good siliconized latex caulk or use a product called
Grab made by Loctite. This is my Tested Tried & True method of painting over
wallpaper.
It is sure easier than repairing micro-cracks and other hidden defects
on an old plaster wall!!!! And on drywall walls that were papered frpm
new and therefore not neccesarily finished to the best finish. If a
drywall wall was not properly primed before papering you are NOT going
to get the paper off without damaging the paper coat of the drywall no
matter HOW carefull you are.
Just don't try paintiung over the wallpaprer with a water based latex
without the oil based or KILZ primer first!!!!!!! Bubble city!!