Well, this was unexpected...

[Darksev]

So, last night my Cousin drops off a new sharp for me to play with. It's an old (50ish years or so) pen knife that at one point belonged to my granddad, before my Uncle ended up with it. The knife itself looks to be reasonably inexpensive (stamped steel liners with turned up tip bolsters, USA marked blades, aaaaaand that's it.) But unlike the other one I've seen like this, the blades are actually ground on both sides, and they are carbon steel. (last time I saw one the blades were stamped out and only ground on one side, and stainless).



Any ID would be nice, but that's not the point of the exercise. I decided to try a new way to clean up all the rust and corrosion on this puppy. The other week I bought some plastic and ceramic media for my rotary tumbler, to aid in finishing some Ti parts I was working on. I took these:



and tossed them in with the green plastic cones for about 7 or so hours. I also tossed in a pretty nasty looking screwdriver blade from a TL29, just to see what happened. I used the media wet (water + a tiny drop of dish soap). This morning, I opened up the tumbler, poured out the contents and was really surprised to find this:



Aside from being completely clean with no major structural issues (slight dulling of the cutting edges, oh well) they are entirely black. It's a pretty resilient coating too, I scratched at the TL29 blade with a scribe to see. It doesn't flake off or anything. Anyone run into anything like this before? The next step is fine ceramic media with simichrome in it, so I assume that will get me back to steel colored, but in the event I ever want to blacken a small blade, I now know how

[glennbad]

Wow, that looks like some kind of crazy patina...

Looks nice and coated, however. Weird...

Glenn

[Darksev]

After about 4 hours in the ceramic media with simichrome this is the result. It's not mirror for sure, but it's a wonderful flat grey now, for the most part. I think I'll do another couple hours, then maybe switch over to steel shot and see if that burnishes at all

[philco]

Adam,

Maybe you can sell that process to Case to use with their "Pocket Worn" line of knives. Just think, you could go buy a brand new knife with a well worn handle and blackened C V blades. It would look just like one that had been carried for several years in a working mans sweaty pocket.

BTW I never quite understood the "Pocket Worn" marketing concept. Of course I never understood buying jeans that already had holes in them either.

Phil

[Hukk]

I wonder if the minerals in the water caused that patina? It's a nice look.

[Darksev]

mineral content is possible. I have alot of minerals in my water, Iron included. I *think* I used stuff out of the britta though, so who knows. After 8 hours in with the stainless shot, they now have a nice sheen to them, not a mirror polish, but I think they look great, well used, like they are. It's hard to see in the pics, but they are quite shiney