Hey guys, a buddy of mine gave me a Wort chiller to use. So I figured I would try to clean it up good before I use it. I have boiled it in a vinegar/water solution twice, and scrubbed it with a sponge and B-brite. Each time when the I dry it off with a paper towel, there is a little residue on the paper towel. I have attached a picture of the chiller and the paper towel to get some opinions on if everything is good.