Preparing The Plaster Surface

That old plaster wall or ceiling you're about to renovate needs to present a tight clean surface to work on.

Are you ready to start? Let's go.

Be on the lookout for these:

--- scaling paint

--- dusty, powdery surface

--- bits (or more) of old wallpaper

--- smoke residues, dirt

--- brown water stains

1. For loose paint, grab that paint scraper or wire brush and let 'er rip. Then wipe down with a damp sponge to catch those last paint or dust particles. In some cases, you may have to pry off some loose scales with a knife blade. When you're satisfied, tap on things where you worked and listen for a hollow sort of sound. If it sounds tight, it probably is.

2. Dusty, powdery areas. Wire brush it well (wear a face mask). Clean after with a wet sponge. After the area dries, test to see if you got it all. When you are satisfied, you may choose to brush on a coat of fast drying oil-based primer/stainkiller for extra security.

3. Old wallpaper. Can't leave ANY of it. Pieces of wallpaper have a tendency to come loose or blister under your repair compound. Dampen, then remove. Use a stiff putty knife. Try to avoid gouging the plaster.

see How to Remove Wallpaper

4. Smoke residues (or dirt). This condition can be obvious, or it may be fairly subtle. Common sources: fireplaces/wood stoves, oil heating systems, tobacco.

A couple of easy tests. Lick your fingers and wipe. Can you write your name? Or, with warm water and a sponge, wipe down an area. Squeeze out the sponge in the water. Does the water discolor? Ceilings are often worse than walls for smoke.

To remedy, you wipe down the whole area with warm water and a sponge, changing your water as needed. This may require a couple of washings, depending on how bad the surface is. A commercial cleanser in your water may be helpful. Trisodium phosplate (TSP) is cheap and effective, but you have to rinse the whole area with clean water later to remove residues of TSP. You don't want any adhesion problems later with your repairs.

The same goes if you use any kind of soap in your water. Fortunately, there are some inexpensive commercial cleansers you can add to your water that don't require clean rinsing afterward. Dirtex is one.

A word of caution: When you wipe down old plaster with water, if you notice the paint bubbling easily, this could point to an underlying problem with CALCIMINE.

5. Water stains, usually a nasty brown or grey. Be alert for sagging plaster when you see water stains. Pretty common with old plaster ceilings. (See Sagged Ceilings)

If you are lucky (and assuming the water source has been stopped), you may only have some discoloration. If the old paint is still tight, brush on one or two coats of a quick drying oil-based stainblocker.

If the old paint is loose, remove all you can, wire brush any powder or dust, clean with a wet sponge, let dry then put on the stainblocker. The stain is usually in the plaster too.

CAUTION: Environmental hazard. It is common for old plasters to have an initial coat of oil paint with lead. Wear a good mask when scraping or wire brushing old painted plaster. I would suggest you put down some throwaway plastic drop cloths under your working area. When you're done disturbing the old paint, roll up the plastic and discard appropriately.

Don't forget to close doors/mask openings to contain air flow during this time. Keep children out of the work zone during this part of the renovation project.

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You want to hang wallpaper over your plaster? But there's a problem. The existing texture on that wall is pretty rough. Here's how to deal with this:

see prepping rough plaster for paper