This is a little cauldron I found lying around. My youngest daughter used it when she attended Hogwart's. She isn't interested in potions any more. (sigh) So I don't think she will mind if I use it for rust dyeing.
It must have some power in it because I put a plain white silk satin scarf, some vinegar, iron filings and sumac juice in it and a magical transformation happened to the white scarf.