Fire residue?

This was found in a closet on an exterior wall. There is no known vapor/moisture barriers present. Has anyone experienced this type of marking. It appears to be in other areas around wall hangings. Could this be from candles/incense or fire? Pressure differences?

Yes, it looks like ghosting…google it.

“The marks on the walls & ceiling are partially caused by moisture condensation at these slightly less insulated points in your building envelope. Then the dust sticks to the moisture at these points over time and shows as a stain. Prolonged moisture on these areas also promotes mildew growth on these long-lasting moist spots just like the darkness that grows in a bathing shower when it remains wet.”

Yes I’ve seen that too. It can be caused by candles indirectly as they produce water vapor which adds to the condensation and soot which adds to the stain. (probably many romantic nights worth :wink: ) The ghosting occurs frequently at fastener, as in your picture, and at framing members where thermal bridging takes place.