Your Place: Ceiling 'ghost shadows' might not need painting

A few weeks back, I replied to a reader's question about "ghost shadows" on his ceiling.

It isn't as spooky as it sounds. The reader was asking about paint he could use to hide the lines, which reappeared after he had painted the ceiling three years ago.

Of course, I responded to his request for a paint recommendation by suggesting a shellac-based product that I have used to cover water stains from leaks that have been repaired and to keep knotholes from bleeding through finish coats.

Harris Gross, a Cherry Hill home inspector, saw the column and offered that the "ghost lines" the reader was trying to cover with paint "are simply the collection of airborne particulate and can simply be cleaned off."

Painting is not necessary, said Gross, of Engineers for Home Inspection.

He suggested that the ghost lines were more noticeable now because a gas fireplace has been operated during the home-heating months.

The discoloration is often heaviest nearest the fireplace and lessens as one moves away from the fireplace, he said.

Here is what Gross said in a home-inspection report regarding such discoloration, which people often confuse with soot contamination in a house:

"The 'shadowing' present on the walls and ceilings is the result of the collection of airborne particulate.

"Shadowing is a term used to describe the collection of airborne particulate on interior surfaces where the particulate has collected as a result of temperature differences in the interior surface.

"The surface where the wall is well-insulated does not get cold enough to allow moisture to condense. The surface where the wall is not well-insulated gets cold enough (below the dew point) that moisture condenses on the surface.

"The airborne particulate adheres to this condensation and collects over time, resulting in 'shadows' on the other side of the home's framing members.

"Exterior walls and ceilings (ceilings with an attic on the other side) are by far the most common locations for shadowing."

Good to know. It certainly will save on painting.