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Preparing Walls
for Wallpaper and Paint
When considering a
painting or wallpapering project most of us focus on colors,
patterns and finishing the walls. But most experts will tell you
that actually painting or papering is only half the job in getting
professional results. In fact, some say that for every hour you
spend painting or wallpapering, you probably need to spend about 3
hours preparing your walls and woodwork. That's what we'll look at
in this section on preparing walls for paint and wallpaper.
WARNING: First, you should be aware of
some potential risks in older homes. If there's any chance the
paints you're dealing with were made before the 1978 banning of
lead-based paints, treat them as if they contain lead and/or have
them tested. There are extreme health hazards associated with
lead-based wall paints, especially sanding them. For more
information, contact Environment Canada.
Removing Old Wallpaper
Ideally, any wallcovering you have to remove will come off as easily
as most newer vinyl wallpapers which usually peel off with a minimum
of effort. To remove wallpaper, just loosen up a corner and start
pulling, possibly using a 4" or 6" putty knife to help pry it off
the wall. With peelable papers, a top layer peels off, leaving a
thin backing glued to the wall which requires a little more effort
to remove. However, most of the older wallpapers require a lot more
effort.
Sanding Old Wallpaper
One of the best ways to loosen up old wallpaper glue is to first
moisten the paper with a wetting agent. But many wallpapers are
coated with a thin layer of vinyl to make them waterproof, so
they're impervious to wetting agents. If that's the kind of paper
you're removing, you should first sand off as much of the vinyl
coating as you can -- removing as much of the gloss as possible and
exposing the paper below.
Perforating the Surface
You can also use a tool known as a paper tiger, which basically has
a pair of wheels with tiny, sharp teeth that perforate the paper and
allow the wetting agent to penetrate into the glue layer(s). Just
roll it across the wallpaper, covering the whole surface with
perforations. You can also substitute a utility knife to score the
paper. Cut in a series of shallow, criss-crossing lines to let the
moisture penetrate.
NOTE: The key word is shallow.
If you cut too deep, you may damage the wallboard or plaster below.
Moistening Old Wallpaper
As a wetting agent, you can use water, a mixture of water and
vinegar or wallpaper removers which are usually mixed with water.
And you can apply it with a sponge, a paint roller, a mister or a
sprayer. Whatever you use, give the wetting agent time to loosen up
the glues and apply more if it dries out before it's done the job.
Scraping Wallpaper
Once the glue loosens up, start prying up the old paper with a
wide-bladed tool. If you're lucky, the paper will now come off
cleanly. But more often than not, it will come off in stages with
some parts of the paper almost falling off the wall and other parts
still sticking fast. So remove the loose paper, moisten the
remaining paper again and scrape that off as it loosens. Don't be
surprised if it takes several tries or you discover several layers
of wallpaper.
When Not to Remove Wallpaper
If you find that the wallpaper is really stubborn, it may be glued
directly to drywall. In this case, it's virtually impossible to
remove the paper cleanly without pulling off the drywall surface.
The best alternative is to put a new layer of wallpaper directly
over the old one. First sand down the old wallpaper, then apply a
coat of primer before papering or painting.
Cleaning Walls
Thoroughly clean the walls before painting or wallpapering. This is
an often overlooked step, but doing so will ensure better finishing
results. If the wall had old wallpaper, a residue of old glue
probably remains which should be removed. If it's just old paint,
there's probably a layer of grime that prevents new paint from
bonding. In either case, the best cleaning agent is often TSP (trisodium
phosphate). Mix TSP with water and sponge it over the walls and
woodwork.
NOTE: TSP is somewhat caustic,
and will actually remove the gloss from old paint. That helps new
paint because glossy surfaces don't bond as well. But be careful not
to get TSP on painted surfaces you want to save. As always, follow
all package directions.
Repairing Damaged Walls
Ripping off old wallpaper may reveal wall damage that the paper was
hiding. Such areas should be repaired before moving on to the
finishing stages. Narrow cracks and small holes are easily repaired
with joint compound, or ready-mix spackling compounds sold in small
containers at home centers. Use a putty knife to apply the material,
daubing on enough to fill the damaged area. Wipe away any excess
with a rag or damp sponge and allow to dry. Some products may shrink
as they dry and require a second application to fill completely. On
wider cracks, remove any loose paint, plaster or drywall material
before patching. You can also reinforce the repair by laying a strip
of fiberglass mesh tape over the crack and embedding that in the
patching material. After it dries, apply a second coat of compound
to cover the tape.
Repairing Larger Holes
On larger holes, you can use metal mesh repair patches with a sticky
backing that adheres to the wall surrounding the hole. Finish that
patch by covering it with spackling or drywall joint compound,
applied in two or three thin layers. Another option is to patch it
with a piece of drywall: First, trim the drywall back from the
damaged area, leaving a rectangular area to fill. Then you need some
kind of backer inside the wall to support the patch. You can set one
or two plywood strips in behind the hole and secure them by screwing
into them through the front of the drywall. Cut the patch to fit the
damaged area. Screw that into the backer. Fill the joints between
the patch and the existing wall with joint compound. Embed mesh tape
over the joints to reinforce them. Finish the joints with one or two
more layers of compound after the first layer dries.
Sanding Walls
After removing wallpaper and/or patching cracks and holes, lightly
sand the entire area to be painted. If patched areas dried
especially rough and don't respond to light sanding, try using a
6-inch taping knife as a scraper to knock off the higher, rougher
spots of dried joint compound. Use caution though, because it's easy
to gouge the patched area with the corners of the blade. Then use
the open weave type of sand paper designed for drywall surfaces to
finish smoothing out the patches. |
