This "mold" won't scrub off...is it something other than mold?

[Jack B.]

Tenant moved in and said there is mold in Washer. I go to take a look and scrub it off with a bleach and baking soda paste. First wipe it with a paper towel and bleach and NOTHING comes off. It's completely clean. SO I use the bleach and baking soda paste with a scouring pad and scrub for a long time, even let the solution sit on it for a while. Nothing comes off. Some of the stains are dark some are yellow. What is this? I bought a mold test kit, I will go there and test it but I'm starting to think this is NOT mold. But what is it? Some of the stains are dark and some are yellow. And how should I proceed from this point? Liability worries me....she has a baby...

[JD Martin]

Mold and mildew will stain even when the spores are no longer present. So yes, it is likely that it was mold or mildew, and it is likely that it has stained the plastic & rubber in such a way that you will not get the stain off. Heavy sodium hypochlorite will kill any mold or mildew spores out there, as chlorine kills virtually anything that it comes into contact with (some protozoa and cysts can escape in water). Use the strongest bleach you can buy - some of the cheap brands the % of sodium hypochlorite is cut with water - and it will be safe but aethetically unpleasing. You will have to then make the judgement call how to proceed. 

PS: This is pretty common with front-loaders, especially if the previous tenants left the door closed all the time. The rubber seal around the outside gets stained. Mold and mildew come in lots of colors.