Well I tried it. I used a q tip and carefully applied brasso (a little at a time) to the zip only, (not the gold plated pull as I think it will strip the plating). I did it in small sections and made sure not to get it on the material on the zipper or the leather. I then used the other side of the q tip to wipe it off and then buffed it with a silver jewelry cleaning cloth. It did a pretty good job and so much black stuff came off. My zipper shines now and it zips and unzips just as great as it did before! My wallet and mini pouchette looks refreshed!