Quoted from RC_like_the_cola:I bought a 1 pound tub of flux about 6 months ago. It's been about a month since I've needed to use it. I went to do so, yesterday and noticed a green speck of mold on the inside of the lid. Looking in the tub, there are tons of white mold spots all through it. Is this normal? I keep it in my climate controlled home, so it isn't getting extreme temp changes. Now I gotta buy new stuff.
I wonder if there's some contaminant that has gotten into it. You haven't been eating toast while soldering, right? 
