Cleaning dark spots from highly polished blade
- Thread starter johnlk99
- Start date
- Joined
- Dec 21, 2006
- Messages
- 3,158
The first thing I would consider is the easiest/simplest. That is Bar Keeper's Friend. It is a powder (also comes as a liquid) that uses oxalic acid to remove rust. You make a paste from the powder, apply to the blade and let it sit for a minute or two, then wipe or scrub off. The thing is, depending on how deep the rust goes into the steel, it may be "pitted". The only way to get rid of the pits is to polish the blade. If they are very deep, then you might have to resort to a blade re-finish. But, at least the Bar Keeper's Friend will remove the black spots to where the imperfections will not be as noticeable. (I'm not a fan of mirror polished blades, especially mirror polished carbon steel. If anything happens like shown with that knife, any sort of scrubbing to remove the black marks will likely scratch the blade polish. That's why Bar Keeper's Friend is so highly valued...it uses a chemical reaction rather than a scrubbing action like Comet/Ajax or other abrasive products).
- Joined
- Apr 12, 2009
- Messages
- 13,197
The high polish on the blade should make it simpler without altering the existing finish, using polishing paste like Flitz, Simichrome, etc. The description in the named auction states 'a few spins' on a buffing wheel could clean it up; that might work too, with some polishing compound (white rouge, etc).
It's possible, maybe likely, there'll be some pitting left behind, even after polishing away the dark oxide or rust in the spots. But the polishing should help make the spots (or pits) less conspicuous. Only way to remove the pits is to sand the steel to the depth of the pits, and completely refinish and repolish.
BKF (Bar Keeper's Friend) can work very well to remove rust. But it's also capable of etching steel; you have to be very, very careful with it, so it doesn't alter the high-polish finish in it's own way. An 'etched' finish often looks like bead-blast finishes, kind of a dull matte grey; it's easier to conceal on satin or bead-blast finishes. But on high-polish finishes, any subtle etching will stand out more. Heed the instructions on the container, which recommend not leaving it in contact with the steel for longer that maybe ~ 60 seconds or so, then rinse it thoroughly away.
It's possible, maybe likely, there'll be some pitting left behind, even after polishing away the dark oxide or rust in the spots. But the polishing should help make the spots (or pits) less conspicuous. Only way to remove the pits is to sand the steel to the depth of the pits, and completely refinish and repolish.
BKF (Bar Keeper's Friend) can work very well to remove rust. But it's also capable of etching steel; you have to be very, very careful with it, so it doesn't alter the high-polish finish in it's own way. An 'etched' finish often looks like bead-blast finishes, kind of a dull matte grey; it's easier to conceal on satin or bead-blast finishes. But on high-polish finishes, any subtle etching will stand out more. Heed the instructions on the container, which recommend not leaving it in contact with the steel for longer that maybe ~ 60 seconds or so, then rinse it thoroughly away.
Last edited:
David Martin
Moderator
- Joined
- Apr 7, 2008
- Messages
- 19,520
I would go with hand working Flitz if you don't have buffing wheels. It will do it. DM