Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing since 1989
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Polishing a knife to a mirror finish
Q. I have a problem with polishing my butterfly knife for my collection. It has a lot of major scratches in it and I want to polish the steel back to a fine, nearly seamless finish. I have inquired about chemical solvents, but I want to use something safer than that if I can. I have used a sanding wheel to take off the outer layer of enamel and steel because I want it to be a metal color instead of the color I bought it in but the sanding wheel left some very ugly scratches that I can't get off. The problem is that a butterfly knife has a couple pins in it that must be right for it to function properly. Does anyone have any suggestion for me?
Ben L.hobbyist - Columbus, Ohio, United States of America
2004
A. It might have been a better idea to remove the colored paint with a solvent than with a grinding wheel, but you can't remove the grinding wheel scratches with a solvent--they must be mechanically removed. Polishing is a multistep process utilizing buffing wheels and compounds. Basically, each step must remove the scratches from the previous operation, leaving only its own smaller scratches; and this process is continued until the item is sufficiently polished. If you search the site with a good deal of patience, you will see a lot of detailed advice from experienced polishers
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2004
Q. I have a knife blade made of some kind of very hard carbon steel. I want to put a mirror finish on the blade to get it ready for engraving. I have hand sanded the blade all the way to 2,000 grit wet dry and buffed with a brown jewelers rough. After all of this I can still see tiny scratches that I just can't buff out ... any ideas would be appreciated.
Sanborn Shawn- Lodi, California, USA
March 31, 2012
A. I'm assuming that you are hand sanding this blade, well it sounds like you shifted up in grits too fast, depending on the depth of the scratches go back down in grit and work back up. Make sure you are using a sanding block, go check out the equipment at any body shop supply store for finishing clear-coats and decide.
In addition there are several engineered abrasives that are available for purchase that can make this go a bit faster. I believe that Norton makes sanding belts that are fine enough for doing the final finish on what you are after.
- Lenoir, North Carolina
April 16, 2012
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