Thread: What can cause that dark dots

this happened on the basement living ceiling mostly along the exterior wall. 16 yrs old 3 stories detached I thought that could be some kind of lights installed before. any idea?

Originally Posted by Peter Louis

this happened on the basement living ceiling mostly along the exterior wall. 16 yrs old 3 stories detached I thought that could be some kind of lights installed before. any idea?

Flash photography can skew photos, so I'm not sure what you're seeing in person. Could be anomalies, could be nothing....

Dom.

Originally Posted by Peter Louis

this happened on the basement living ceiling mostly along the exterior wall. 16 yrs old 3 stories detached I thought that could be some kind of lights installed before. any idea?

LOVE THESE "what is it"'s

Candles?

Color and near walls suggest wall paint daubed on ceiling but the shape of the blobs suggest other than paint mishap. They don't look like insulation voids that can cause ghosts or shadows. They do look a little like paint "holidays". (wrong sheen) Sample with moisture detector would be my first exam. If there is an attic above, then an inspection there is next. They don't suggest mold or leakage from above, but you never know. If dry and not accessible from above, as a home owner, I'd paint with a stain killer and see if they re-emerge before I start cutting holes.

Its where they roll painted the walls and hit the ceiling and then touched up the paint… SWAG!

It looks like bleed through, either a stain from above, (i.e. dead mouse in attic) or drywall was contaminated with oil or some other form of contaminate before being installed, and likely poor priming before painting did not hide it stain.

Originally Posted by Scott Patterson

Its where they roll painted the walls and hit the ceiling and then touched up the paint… SWAG!

that's my guess from what I can see.......and ceiling are very hard to touch up successfully

- - - Updated - - -

Originally Posted by Scott Patterson

Its where they roll painted the walls and hit the ceiling and then touched up the paint… SWAG!

that's my guess from what I can see.......and ceiling are very hard to touch up successfully

Ghosting..
http://www.inspectionnews.net/home_i...s-ceiling.html

I concur with Marc but will relent to give a full nod to the hypothesis.


Ghosting hypothesis:
Looks like candles convection.

Yes it can be from candles and is called Ghosting, the real name is Brownian Motion.

I do not know if I personally would consider the particles randomly placed.
With candles, I believe it would be considered a form of man-made pollution and thermal tracing.
Other forms of ghosting can be linked to thermal bridging, thermal tracking, electrostatic deposition.

For your info.


December 21, 2006
Abstract:

This digest offers a detailed explanation of the causes of carpet discoloration, particulate deposits on surfaces and "ghosting" of wood stud members on the interior gypsum board surfaces of exterior walls.

BSD-150: Black Stains on Carpets and Ghosting of Framing | Building Science Corporation

Ray,
Good solid description.
Great articles as well.
I enjoy the narration and the descriptive narrative: (4) four Deposit Mechanisms.
I could not conceive it as random molecule displacement, but rather home sciences with laboratory testing/modeling.

How I interpret the article is, there are 2 mechanisms.
1: Filter.
2: (Plate Out.)

Plate out has (3) roles in the attraction or flow mechanism: (1) Electronic, attraction. (2) Temperature, cold surface. Likely a dew point & convection. (3) Impaction motion.

Thanks.