Question about marks on drywall

[shermanator]

Got a question for the CP faithful. I painted my walls a few weeks back, and I've noticed a few marks like the following. Not sure how well it shows in the picture but it essentially looks like I spilled something on the wall and let it drip for a second.

Does anyone know what produces these? Is it due to the humidity levels we've had recently?

[GoinAllTheWay]

Probably something that was on the walls prior to you painting. Did you clean the surface with TSP beforehand? Certainly not required but can remove any grease/dirty areas prior to a new coat.

[puckluck2]

Is this in an area where some sort of detergent could drip onto the wall? That's likely from a prior stain and in order for it to not show you need to spray the stain area with px primer and then repaint the area. At least that's how I do it.

[Buff]

Had something similar at my old house. It kept getting more noticable over time so we painted over it. It showed up again, so we sold the house... Okay, that isn't why we sold,we were upsizing and threw on a quick coat of cheap paint to help maximize the attractiveness of the house for sale, but painting over it didn't hide it, but did make it less noticeable. I assume the previous owners did the same thing.

[Wormius]

Originally Posted by GoinAllTheWay

Probably something that was on the walls prior to you painting. Did you clean the surface with TSP beforehand? Certainly not required but can remove any grease/dirty areas prior to a new coat.

I would agree with this. Painted our kitchen a while ago and didn't scrub enough with tsp, and noticed these streaks as well. I assume we painted over where some oily sauce or whatever that got splattered.

[Huntingwhale]

Looks like a murder stain

[speede5]

Use a sealer primer like zinser or killz and then repaint. Water or oil stains will bleed through just about every paint out there.

Don't worry if it looks like it bleeds through the sealer before you paint, it will, but the stain is 'trapped' in the sealer.

[normtwofinger]

+1 to the post above. Killz and Zinser will prevent any stain from bleeding through. Expensive stuff but works.