Etching O1 / Patina

[silver_pilate]

I'm currently working on a knife for a customer who plans on giving it to her husband for his birthday. She wants him to be able to use it as a daily use knife‚ and there is a possibility that he will not take the best of care of it. Because of this and the fact that I'm using O1, I suggested a patina for a little added rust protection.

As I've worked on the knife, it is turning out so well that i almost hate to cover it up with a patina. At a hand sanded finish of 600, how corrosion resistant is 01? My thought is that a patina or etch of some sort would give a longer window before rust sets in if the guy doesn't oil it up often.

I've used a splotched mustard patina in the past‚ but for this knife, I'd rather go with something a little more uniform. The blade will be fully hardened and tempered with the handle and spine drawn back with a torch. What's the best way to get a good uniform gray on O1? I've got fe-chloride as well as vinegar.

What do you think?

Thanks!

--nathan

 

[RSMITH]

O1 will rust in a matter of hours & will be pitted in no time if left wet.
The only way I have seen around it, is to coat the blade with duracoat, gunkoat, or ceracoat. even then the edge will rust, but at least the edge should be "ground" at the user level.
If I was making a knife for someone that was not going to take care of it, I would probably use stainless. (unless it was a big knife, made for hard use)
Randy

 

[stephanfowler]

the best patina comes from age, however, the new owner would have to be responsible enough to clean and oil after using the knife, and that doesn't seem to be the case here

if it were me i would consider a cold bluing solution, mostly because it can be very easily reapplied by the new owner with no tools required (it is however a less durable finish than hot bluing, i know)

 

[silver_pilate]

I don't think the guy is going to be a total lush with the knife. I'll give him reasonable instructions as to the care of the blade. I've seen O1 rust in minutes in a roughly ground state. However, I also have a couple of shop knives I made in O1 that have had no trouble. Given, I've kept them dry, wiped off, and oiled every once in a blue moon. Also, a camper I've used a good bit has help up very well with a mustard patina. We are fortunate out here to have typically very low humidity.

I'm just stepping into the world of stainless, so I don't feel confident in making a knife for a customer in stainless until I've done more testing for myself to ensure I'm doing it right. Also, I don't have any 154CM in stock right now.

I've no experience with a cold blue. Any other ideas for a more traditional etched on patina? I like the look of Brian Goode's O1 (Blgoode).

--nathan

 

[Alarion]

Etching pits the metal to a microscopic level, so makes the metal even more prone to rust.
The more polished the metal is, the more resistant to rust.
Parkerizing is another thing. The etched surface gets a finish of passivating oxides that protect the metal from further oxidation, and the microscopic pitting soaks in oil which adds even more to rust resistance.
You can try parkerizing (brownells has very good kits for this operation).
A pass with an oiled brush every now and then is all needed to keep the knife from rusting.

 

[silver_pilate]

I know a true use patina serves to inhibit the more aggressive red rust, but I've seen differing opinions on whether an accelerated (vinegar, mustard, onion, etc.) patina will do the same thing. From what I've read, the concensus is that it will slow the onset of rust, but only taking care of a knife will truly prevent rust. Obviously, with most any carbon, non-stainless steel, cleaning and drying after use as well as occasional oiling are the best ways to keep the knife in good shape. If the customer doesn't want to do that with a knife made of O-1, then rust is what he'll get, and it will be his problem, not mine. I've not used bluing solutions before, and I don't really want that look on this knife. If I had more time, I would experiment more, but this is a rush order.

The understanding I had was that the controlled oxidation of the steel in an accelerated patina would help slow the more damaging red rust from getting a foot hold, even though it will not fully prevent rust. I guess I'm just wanting that extra time that a patina might give vs. no patina.

Am I right on this, or am I way off the mark?

--nathan