Before we moved out of our old, moldy farmhouse (in Oct 2010), we filled holes and painted the school room (the kids had used Sharpie on the walls!).
We had not used the Spackle since that time.
Last week, when moving last minute items from our more recent rental Paul opened the can...
the insides were COVERED IN BLACK MOLD!!!
Be careful when you have black mold, my friends! It is toxic stuff and it is super hard to get rid of!