Polishing out scratches in a steel knife blade just takes some sandpaper, Simichrome, and elbow grease. I experimented with polishing by hand and came up with some simple recommendations.
There are usually 2 obstacles to getting any task done. Not knowing where to start and worrying about “ruining” whatever it is you are working on. I know how to sharpen a knife with a file and with a stone. But I have not done much cosmetic work on knives. So I decided to venture into knife repair, and learn how to remove scratches from a knife. I started with a badly scratched kitchen knife because I didn’t care if I ruined the way it looked. It was just a kitchen knife, not a rare collectible Bowie. And also, this particular kitchen knife was really messed up. It is a Gerber Balance Plus 1401 10” Cooks knife made of high carbon stainless steel.
Please note, I did not scratch the bejesus out of this knife. I got it second hand. It is hard for me to imagine how a kitchen knife could become so damaged. Pretty much every bit of the blade was criss crossed with big and little scratches. But that made it a good place to practice.
Let’s review the rules of every DIY project:
Rule #1, get started.
Rule #2, don’t ruin it.
In the spirit of getting started without ruining it, I began my knife polishing project by trying Simichrome metal polish first. I recently discovered Simichrome polish, which is a metal polish that also works on a variety of other hard surfaces. It does a good job at really bringing out a shine, and it is very mild. I thought I would try the mildest polishing technique in my arsenal first because that would have the least chance of damaging my blade.
Though I could not feel the scratches on the blade with my finger, it soon became obvious that the scratches were too deep for Simichrome.
My next blade polishing technique was to use sandpaper. I started out with 400 grit sandpaper. That too turned out to be too mild to make rapid progress. From there I moved down to 240 grit sandpaper. The 240 grit did a nice job of removing about 80% of the scratches. But many of the scratches didn’t seem to be much phased.
I then started working on the knife with 150 grit. I really thought 150 grit would be too coarse, and that it might put deep scratches of its own in the blade. But it worked nicely. And if I had any 100 grit, I would have given that a try to speed things along.
After working for a while with 150 grit, I then moved back up through 240 grit, 400 grit, and then up to 1500 grit. After the sandpaper I went back to the Simichrome polish. The result is that the knife looks much much better than it did before.
As you can see, I did not take out every scratch, mainly because I wasted so much time experimenting with added steps that I didn’t really want to back up to heavier grit and remove the last of the scratches. But most of what remains is only visible in a very high contrast environment. The knife looks almost new now, and I actually enjoy using it more now. I didn’t realize that the ugliness of the blade bothered me before, but it did.
Here are my recommendations for polishing a knife blade that is badly scratched:
Don’t worry about causing more damage by using too coarse of a sandpaper. Next time I will start the process by sanding with 100 grit sandpaper to remove the heavy damage quickly. The way I did it, starting with the mildest, working all the way through to the roughest, and then back through to the mildest was very tiring, and ended up taking about 2 ½ hours. Starting out with 100 grit and going up as needed would probably only take 1 hour or less.
Simichrome works well as a polish on metal and micarta. The only problem I had was where to buy Simichrome polish? Orchard Hardware (OSH) did not have it. O’Reilly Auto Supply did not have it. I finally found it at Ace Hardware, locked in a case. The Ace guy, who uses Simichrome himself, told me that the company that makes it doesn not have a distributor, so stores need to order it directly from the manufacturer. If your normal hardware store doesn’t have it, I would order it from Amazon (always support your local hardware store, or one day it will vanish, and your house will fall down for lack of one damn bolt on a Saturday afternoon).
Knife Polishing and Scratch Removal Supplies:
- 100 Grit Sandpaper
- 220 Grit Sandpaper
- 400 or 600 Grit Sandpaper
- 1000 to 1500 Grit Sandpaper
- Simichrome metal polish
- cloth diaper, old washcloth, or similar cloth for applying Simichrome
- disposable rubber gloves – optional but probably good to use when generating metal dust and using things like Simichrome.