black dust, is it mold !!!!!

[Fred]

I found this out with Google a few days ago: If you put bleach on the black substance and if it turns clear than its mold. This maybe a false positive perhaps someone else in the group has another method other than taken it to the lab for testing.

[yo]

First off I have a Raised Ranch and I have noticed some mold in my basement closets. I have since cleaned this out but I continue to get a black greasy dust like substance all over my basement only. I know the basement is a little humid and I will be taking the appropriate steps to control the humidity. Is this black dust that I have been getting all over my windows, back of the fridge, on top of my baseboard heat and on the walls some kind of a mold or is it something else. The gas furnace and water boiler are located in the basement in a separate room, perhaps I need duct cleaning.

Any advice would be great as I have no idea what is causing this. I have a tenant moving in soon and I need to fix this situation.

[yo]

Thanks, im having someone look at the furnace and water heater tomorrow. Its possible that it is soot

[Norminn]

Mildew would be expected with dampness, esp in basement and bath. The other locations seem strange to me. Do you burn a lot of candles? I would, for sure, have the furnace and water heater checked right away.

Scrub the basement with bleach, water and detergent and dry out well, use dehumidifier if necessary.

I've never seen mildew on windows or back of fridge, so I would be very concerned that it is soot.