I've heard this process applied to gun parts, but never to knives. Gun aficionados seem to think its about the most corrosion resistant traditional coating method there is. It leaves a real nice blue/black finish and (according to the few accounts I found) can even bring out the pattern in damascus similar to a more standard etch.
The general process goes as follows:
1. degrease the part COMPLETELY, as in soak in acetone, and wear latex gloves handling it.
2. brush on a light coat of a rusting agent (often a dilute mixture of hydrochloric and nitric acids, but anything that makes rust works ok)
3. leave the part sit in a humid environment for a few hours until an even, powdery coating of orange rust forms all over the surface, shorter times make finer rust, but take longer as explained below.
4. suspend the part on stainless steel wires, and boil in distilled water for 1/2 hour or so. This converts the orange Fe2O3 into black Fe3O4.
5. use 000 steel wool to card off the excess coating, anything that won't stick.
6. repeat the process until the coating doesn't get any darker (usually 8-12 repetitions).
7. soak the finished part in oil to saturate the coating, and wipe clean.
Do the gun and knife enthusiasts not share notes? Is it just the time and labor involved? Can boiling water mess up the temper on a knife? I just don't get why there is so much talk about "forcing a patina" and none about a technique that does just that, but with actual corrosion protection beyond what a simple patina provides.
The general process goes as follows:
1. degrease the part COMPLETELY, as in soak in acetone, and wear latex gloves handling it.
2. brush on a light coat of a rusting agent (often a dilute mixture of hydrochloric and nitric acids, but anything that makes rust works ok)
3. leave the part sit in a humid environment for a few hours until an even, powdery coating of orange rust forms all over the surface, shorter times make finer rust, but take longer as explained below.
4. suspend the part on stainless steel wires, and boil in distilled water for 1/2 hour or so. This converts the orange Fe2O3 into black Fe3O4.
5. use 000 steel wool to card off the excess coating, anything that won't stick.
6. repeat the process until the coating doesn't get any darker (usually 8-12 repetitions).
7. soak the finished part in oil to saturate the coating, and wipe clean.
Do the gun and knife enthusiasts not share notes? Is it just the time and labor involved? Can boiling water mess up the temper on a knife? I just don't get why there is so much talk about "forcing a patina" and none about a technique that does just that, but with actual corrosion protection beyond what a simple patina provides.
