Black on walls

Mark Berry

I have a customer that has an apartment on the second floor of his building. He repainted this apartment last fall for his new renter due to black on the walls he thought was from the previous tenants candle burning. The new tenant does not burn candles and does not smoke but black stains are back. I serviced the heating appliance in december of '04. I checked for sooting from the appliance today no soot present. All three of the second floor apartments have electric heaters, only one is black. Any ideas on the source would be great. No soot in any of the first floor apartment.