What is the strange discoloration on my walls?

October 4, 2007 5:18 PM

What is the strange yellow discoloration on the walls of my house?

In several rooms in my house, there is an odd, faint yellowing in the corners of my walls near the ceilings. The walls and ceiling are painted white, and you can definitely see the yellow coming through. It's a relatively new house (built 2003) made of concrete block, with popcorn ceilings and orange-peel walls. We've lived there since the house was built, and the discoloration seems to be getting worse. No one has ever smoked in the house, and we don't have any fireplaces or anything like that. We do know that the builders used the "wrong tape" (whatever that means) in the ceiling in one room, which they came and fixed. There's no discoloration in the re-taped room. Does anyone have any ideas about what the discoloration is? Is it related to the tape, or is the tape just a red herring? Will just painting over it make it better?

posted by griseus to home & garden (6 comments total)

White oil based paint can yellow. Is the paint latex or oil?
posted by LoriFLA at 5:41 PM on October 4, 2007

Could it be water stains?

The tape you refer to is probably joint tape, used to cover and reinforce the seams between sheets of drywall. If they had to re-tape the ceiling they would have repainted it which would have covered any stains (perhaps only temporarily).

If it is something bleeding through the paint and any ongoing problems like leaks have been ruled out or fixed, the stain will need to be primed with something like Kilz in order to keep it from bleeding through repeatedly.
posted by TedW at 6:07 PM on October 4, 2007

Do you burn candles? It could be residue from burnt candles.

Also, sometimes when painted walls are exposed to humidity, the paint can break down and cause a yellow shellac type substance to raise to the surface and dry. I've noticed a bit of this happening in my bathroom and also on the ceiling of a room where I use a clothing steamer.
posted by pluckysparrow at 6:21 PM on October 4, 2007

I'm not sure what would be causing the paint to yellow, but I'll second the Kilz idea. Prime the area with Kilz and re-paint see if that doesn't fix it.
posted by nola at 9:59 PM on October 4, 2007

Since it's not tar from smoking, I agree with pluckysparrow's comment about shellac-ish effects from the paint causing the yellowing. The aging effects of humidity, sunlight, and air flow can vary from room-to-room, also. And, as TedW said, the repaired room was probably primed (if not also mudded again and primed/repainted.)

I <3 Kilz.
posted by bonobo at 11:33 PM on October 4, 2007

We had some water leaks from the upstairs bathroom into the kitchen at my folks' house. The ceiling had yellowing, so water stains are a definite possibility.

It could be smoke stains, but griseus would be able to tell if the previous owner had been a smoker because of the lingering odor of smoke.
posted by reenum at 5:48 AM on October 5, 2007