You've
decided to wallpaper those walls, but what to do about that rough texture?
In my experience, you have two basic choices. You can put a liner on
the wall first (provided the texture is not TOO rough). This mutes the texture and
provides a smooth (relatively) surface to glue paper to.
If you are using the services of a professional paperhanger, you will
be paying for the liner and the hanger's time to put it on. On top of the price to hang
the paper itself. And a paper with a delicate pattern may still show some of the
irregularity.
If you want to save money and prepare the walls yourself, you can
smooth them out by skimcoating the surfaces with all-purpose drywall joint compound.
This is do-able, if you have time and patience.
The first thing to do if you choose this option is to prep the surface.
Remove any scaling paint, powder, dirt, etc. If you have any water stains, I would seal
them by brushing on a stainkiller, preferably oil based.
If you wash down the walls, clean rinse after to remove any soap or
cleanser residues.
I usually go over the surface with a study flat tool to knock off the
worst of the rough points, if possible. This may help to reduce the number of coats of mud
required.
Now you are ready to go. Know that you will have to apply a minimum of
two successive coats of all-purpose compound, or more if the texture is pretty rough.
Tools: a ten or twelve inch broadknife and a mud pan. Or, a plasterer's
hawk trowel.
There is a proper order to skimcoating, to ease your job as much as
possible.
The key here is to make your strokes all go in the same direction as you do each coat. For
the first coat, I like to go all horizontally, starting at the top of the wall and working
from corner to corner. Then move down and continue until you have reached the bottom.
After that coat dries, start at the top again and this time make your
strokes vertical, going from top to bottom. What you are doing now is filling in the
ripples that result in the first coat. Let dry.
Third coat if necessary, repeat what you
did when you went vertically.
At this point, you may get by with a good sanding to smooth out tool
marks. If not, do another coat, varying your stroke directions according to your judgement
of what works best. The final step is sanding. Medium grit sanding sponges work well here.
There is another way to do this that may be easier. Lay down your mud
in parallel strips. When they dry, fill in the gaps. You could choose to do each coat that
way. It will take more days to complete the job this way.
Now that you finally have a smooth surface you can live with, be sure
to put a couple of good coats of drywall primer/sealer (PVA) to render the porous surface
fit for wallpaper.
You did it! Now that wasn't too bad, was it?
