Not all black stains are mold
A rampant concern in the real estate industry and with homeowner’s, both existing and potential, would unquestionably be, from my experience, mold. I have had to talk more than a client or two down from the proverbial cliff after finding some organic, fungal type growth in their potential new house. The freak out factor for the word mold is undeniable...
And for all intents and purposes without merit.
Fortunately it seems more and more potential homeowners have become savvy to the misinformation being spread like fungus over ancient leftovers in the back of the refrigerator. Junk science and anecdotal evidence prevails in the mold industry, typically ignoring the variables associated with indoor air quality and health issues. Most disconcerting of all is the real issue is usually not discussed, moisture. For mold is nothing more than a symptom, just like a runny nose.
On a recent home inspection the buyers were mildly concerned with “some mold” in one of the two closets located in the master bedroom. The house was some what older, 1945, and had, according to the buyer’s, experienced some storm damage in the recent past.
The ceiling and upper portions of the walls inside the closet were sparsely coated with what appeared to be at a glance mold. Upon closer scrutiny, a few facts became apparent.
The most obvious was the lack of any definitive water stains, thus basically ruling out water leakage from the storm damage. Further the walls and ceiling are plaster. Plaster does not so readily absorb water like gypsum board.
Part of the closet is located at an exterior wall. The room is second floor so the ceiling is covered by a roof. And this closet, unlike the other closet in the room, has a baseboard heater.
Why is the location of the closet important?
Because in an older house, the walls and ceiling may not be insulated or very poorly insulated. The stains are more than likely due to a phenomenon often referred to as ghosting. The technical name for any science geeks would be thermophoresis. What the stains are not is mold, although there may be some type of fungus amongst the dirt. Since mold requires first moisture, next food and lastly a favorable temperature, there is really no way for this collection of dirt particles to be anything other than that, dirt.
Thermophoresis or ghosting in one form or another is quite common. What has almost certainly occurred in this closet over the years, is household dirt, specifically small particles typically soot of some form, have rode the thermal current created by the heater and stuck to the cold surfaces at the upper portion of the closet. The stains are nothing sinister or unhealthy. What they are telling us, like many stains they have a story, is that the house needs insulation and air sealing.
No sampling, testing or moon suited persons will be necessary. A little soap and water followed by a fresh coat of paint should be all that's needed.