Btw I was told by some guys that these can even stain your sink / bathtub and that it takes a LOT of bleach to get it off. I found it not to be true on mine, but better check. I think if you're stuff is slightly porous you're in trouble, but otherwise no problem. Maybe you could stain it by leaving it long enough, but just to rinse the recipient it's fine. Alternatively if you have a garden or a workshop use it