Today I noticed that my MDF cutoff box was covered inside and out with a white and green powdery growth. I'm not smart enough to determine what it is.

None of the other wood in it had any growth on it - except a piece of MDF.

I checked the rest of the wood in the shop and it all looks fine.

Granted, the conditions are great for this to happen - un-airconditioned garage in south Texas in the middle of the summer following weeks of rain. Temperature in the high 90s and it feels almost as humid.

I'm new to MDF. Is this be expected? 20 years in this shop with never a problem on regular wood, particle and pegboard, plywood, or high density particle board.. There's even lumber here from the last owner that looks like it just came from the lumberyard.

The majority wipes off easily. Plans are for a light wipe-down with bleach and then to poly it.

Comments anyone?