Any advice on how to remove white stuff painted on under wallpaper. I removed wood chip from my ceiling and am finding it too hard to wash off white substance. Apparently you can't paint over it.
Grateful for any replies.
Anne

 

Welcome! The "white" stuff under wallpaper is often the glue used to adhere it to the wall. Steam will sometimes loosen it enough to be scraped off, or products like DIF can help with its removal. You may want to post a couple of pictures of what you see so we can see the same thing. http://www.doityourself.com/forum/el...your-post.html

 

The wallpaper adhesive normally comes off with water and elbow grease. When you can't remove all the adhesive you must coat the wall with either Zinnser's Gardz or an oil base primer. It's best to remove as much of the adhesive as you can!

 

Is the white stuff sort of "powdery" or "granular"? There are all sorts of "removal solutions" out there. You can even make your own but, if it is fairly old, its usually a granular, powdery dried adhesive left from the "install."
A good removal solution is an "enzyme" solution that breaks down the dried up, granular adhesive. I've always used a product called "Safe and Simple". Years ago, professional wallcovering removers got together with Chemists and developed this stuff. It's a California product so it is non-toxic, biodegradable, and has NO smell. @ 2oz. diluted in a gallon of water, it goes a long way and has been my solution-of-choice for many years. Safe and Simple: (1) 16 ounce bottle 603 Removal Solution

You may make up your own with a gallon of water, 2oz of dish soap, and (if I recall) an ox. or two of vinegar.
Is the surface-substrate drywall or plaster?

 

You may apply Zinsser Gardz, as recommended here, which "encapsulates" and seals EVERYTHING, once you are happy with the surface, but if there is anything left on the surface on which you apply this primer, it CANNOT be sanded off, later. This stuff seals everything and works fantastically as a primer before you finish-coat but the surface has to meet your standards BEFORE you use it.

 

Emphasis added

If you are looking at white painted on substance, it may very well be sizing compound used to prep the wall for the wallpaper. It makes the paper easier to remove without damaging the surface of the drywall. This would be found under the glue residue (that is usually quite thick) that I'm sure you have already tackled. IMO - it is OK to paint over sizing without detrimental consequences. If in doubt, use a universal solvent based primer like Zinnser cover stain blocker.

 

Type "what is the difference between primer and sizing" in the search field, here:

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Sizing is watered-down paste. Primer is a paint product, water-based or alkyd-based that is used to seal the surface. Priming is necessary because it creates a vapor barrier on the wall so that the adhesive that is being used to install wall paper is FORCED to dry OUT THROUGH THE WALL COVERING instead of being absorbed by the wall. When the moisture in the adhesive is absorbed by the wall, it creates a bond with the painted wall surface that creates nightmare removal problems. Sizing is good but NOT on unprimed surfaces.

Sizing is a extra step (after priming with something like an acrylic water-based primer that is painted on the wall surface. OR it might be used at a "short-cut" so that the priming phase can be eliminated before installing wallpaper.
Sizing, since it includes paste (adhesive) must be removed from the surface, after the wall covering is removed if the intent is to PAINT, after wallpaper removal. When paint is applied over any residual paste (sizing) left on the wall, eventually the paint will "alligator".

hope that makes sense