Removing scratches on mules

[Skidoosh]

I have some scratches on my blade- my fault for making the sheath a bit too tight. The scratch is horizontal but the grind on the blades are vertical. This is purely a cosmetic issue but wondering if there any suggestions to remove the scratches.

[Bolster]

Hm. Might consider moving the blade vertically over a scotch-brite pad taped to your bench. Scotch-brite is known for its ability to "blend." There are many "grits" of SB and I'm not certain which one would best match, however. I know the widely available green is fairly coarse. But then, so is the finish on a mule, so...

I'll bet Xplorer has good advice, let's see if he'll chime in...

[Xplorer]

There's no easy solution.

My first and best suggestion is to see scratches as a positive sign of use and just go add more by using it more. Like dirt on my mountain bike I prefer to see scratches on a knife as evidence of living life and I'm proud of to have put in the effort and lived the experience.

To address your concern..Your scratch isn't likely to be deeper than the grit level of the bevel grind. You can sand it out with sandpaper on a hard backing. You'll need to match the grit of the original grind if you want it to blend in. You might be able to remove the scratch with Scotch Bright but it will depend on two things. How deep is the scratch and what steel is it? Most likely you will not be able to remove the scratch with Scotch Bright. After you remove the scratch with sandpaper Scotch Bright will be perfect for blending your sanding marks.

My guess would be 120 grit would match up with the grind lines in the Mule, but I'm just guessing off-hand and I'm not certain.

[Skidoosh]

Thanks, I didn't think it was going to be an easy fix. Good suggestions.

[Bolster]

My guess would be 120 grit would match up with the grind lines in the Mule, but I'm just guessing off-hand and I'm not certain.

So: Guessing you'd start with a finer sandpaper and go coarser until you get a match? Certainly not the other way around, since you can always coarsen sand lines relatively easily, right? Is there any geek/nerd way to discover the grit of a particular grind, by examining the grind itself? Academic curiosity only, here.

But it WOULD be handy to know the likely grit of mule grinds...

[TkoK83Spy]

I thought the point of Mules was to be used and abused, tested for Sal and company to gain feedback? Scratches seem like they should go hand in hand with the purpose of the program.

[Xplorer]

My guess would be 120 grit would match up with the grind lines in the Mule, but I'm just guessing off-hand and I'm not certain.

So: Guessing you'd start with a finer sandpaper and go coarser until you get a match? Certainly not the other way around, since you can always coarsen sand lines relatively easily, right? Is there any geek/nerd way to discover the grit of a particular grind, by examining the grind itself? Academic curiosity only, here.

But it WOULD be handy to know the likely grit of mule grinds...

I get why you'd think to start with finer grit. What I've learned from hand rubbing too many blades to count is that hardened steel is stubborn and it takes too much time and sandpaper to start out on the finer side. Trying to remove a scratch isn't going to result in perfection unless you're going to completely re-finish the blade anyway. I would simply start with 120 grit. If it's too course it will be easy enough to step those sanding lines down to 180 if I need to and I doubt I would have to go as far as 240. If I start with a grit that's too fine it just takes too long to get the scratch out.

If you want to make the finish perfect you'll need to sand the blade length-wise until all of the grinding marks are gone. Then step down a grit and sand across the blade until all of the length-wise scratches are gone. Repeat and alternate sanding direction until you get to the desired finish. You'll also want to lay the blade flat on a surface plate and sand the sides in order to clean up the plunge lines.

Those are 120 grit grind lines from my rough grind and that's 120 grit sandpaper on the aluminum bar as well.


This is finished at 800 grit.


But even with all of this talk about how you "could" fix a scratch, I still think adding more scratches is better than removing the first one. :cool:

[Skidoosh]

Beautiful work

[Bolster]

I would simply start with 120 grit. If it's too course it will be easy enough to step those sanding lines down to 180 if I need to and I doubt I would have to go as far as 240. If I start with a grit that's too fine it just takes too long to get the scratch out....But even with all of this talk about how you "could" fix a scratch, I still think adding more scratches is better than removing the first one. :cool:

Aha! Gotcha. Nothing beats experience. Thanks for the explanation!

I gotta admit, one reason I'm a fan of stonewash is that everything is pre-scratched. Do any of you folks do stonewash? I've got a Thumler's Tumbler and some ceramic media from HF and it makes a really nice stonewash...but it does NOT completely cover up the grind lines on a Mule, I learned. You'd have to sand the Mule out finer, as you demonstrate above, in order to get a "grain free" stonewash, I think.

[Xplorer]

I'm a big fan of stonewash as well...for the same reason. IMO the best finish Spyderco has ever put on a knife is the semi polished and tumbled blade on the Slysz Bowie.

I want to (plan to) add stonewashing capability to my shop eventually, but it's going to take me a few more years and will include moving into a proper shop first. It's very expensive and isn't on top of my machine purchase priority list yet. The smallest version of the proper vibratory finisher for making blades of all sizes look like the factory tumbled finish you're used to seeing is about $6500.
https://www.burrking.com/catalog/p-1000 ... g-chambers

I'll be adding a full engraving/inlay station, a pantograph engraving machine and a full size surface grinder before I consider spending that kind of $$ on a noise maker that's guaranteed to irritate my neighbors :rolleyes: .

One thing to consider with putting a tumbled finish on hardened knife blades is that you need to vibrate the blade in wet media for about 12 hours to get a really good finish. If I lived out in the country (where I belong ) I might just let it run "out in the shed" but I live in a townhouse. Vibrating knives for 12 hours at a time would not be a very neighborly thing for me to do.

The HF vibratory bowl finisher will work for putting a finish on small blades, but vibratory finishing and tumbling will not remove the grind lines. If you want nothing but a tumbled finish you'll need to sand those lines away first. Once you sand the lines away, you can use wet ceramic media and after tumbling 8-12 hours (depending on the steel and the desired look) you will have a nice finish. You might want to insulate a box to put over the tumbler to reduce the noise.

[Bolster]

I'm a big fan of stonewash as well...

I’m not an expert and I don’t play one on TV, either, but I can verify several points of what the X-man says above:

YES, a stonewash works much better if the media is wet, and has a little dishwashing soap added. I tried it both ways, and the wet/soap worked faster and gave a better finish than the dry, which was also nice, but slower and subtler.

YES, it takes 12 hours…overnight in my case. Shorter times didn’t do much.

YES it is noisy…at least my Thumler’s Tumbler is…but that’s a $0.3K machine not a $6.5K machine.

YES, I put a box over my tumbler to cut the noise in half. Neighbors didn’t complain but…they could have. My family hated the tumbler and were quick and persistent in telling me so.

YES the stonewash didn't remove the grind lines. I only stonewashed the handle of a Mule, not the blade, and on the handle, underneath the stonewash, I can faintly see the grind marks. Subtle enough I will very unlikely sand down the handle and re-tumble, but, if you look closely, you can see the grind lines beneath.

Let’s just say my stonewash isn’t up to Xplorer quality, but it meets and surpasses Bolster quality.

PS: Love me a surface grinder. Don't have one, prolly never will, but what a wonderful machine. Looking forward to borrowing X's when he shells out for one. (Kidding)