Can an etching machine be used for darkening blades?

S

Storm W

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Feb 19, 2019
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I am doing some little hunters/EDC and was hollow grinding them leaving the oxide rind on fir looks and scratched through the rind. I gave the knife a long ferric etch and was going to give it a coffee soak to make sure that it stays dark. It git me thinking that it might be possible to use the etcher to build up a more durable oxide layer or to get more oxide in the coffee and lock in the color. The way I understand coffee works is to dye the rough surface left by the acid. If that is the case are there possible ways of making it more effective like adding coffee to the ferric and adding a tiny bit of current or something else to lock in the color in a similar way that aluminum is anodized? Isn't that sort of what a coffee etch works anyway?
 
Stacy E. Apelt - Bladesmith said:
Short answer - No.
Try Parkerizing.
Click to expand...
In theory it has to do something. Just because I like to understand things or find different ways to do things I am wondering what it might do and if there could be any utility to it. Has anyone tried using it for something? It should make some sort of change to how steel etches and it should be possible to deposit something on the steel. I would imagine there is a downside since I have never heard of anyone doing it.
 
ive used the mark setting on my etcher and darkened even SS blades kind of gives it a rust brown pitina
 
The biggest issue is current density. At 2amps, the density in the minute area of a logo is high. Over a whole blade it would be very low. Just attaching the lead to the blade and submerging it would anodize it a bit, but it would be slow and the deposit very thin. Maybe a battery charger at 20-30 amps would do something if you wanted to experiment.
 
i "painted" it with the felt marker pad not a submersion setup and you can go back over spots that didnt get as dark as wanted. got to keep adding electrolyte to the pad cause it gets plenty hot
 
This particular knife is M4 and a 2 day soak in ferric did what I needed by making a couple of scratches blend in with the mill finish. It's actually cleaned off all the nice scale and that wasn't what I wanted. It still has that mill texture to it to contrast with the hollow grind. I guess where I was hoping it might go would be to add a rough surface texture that would hold some color from something like coffee or maybe some other dye. It would give me the option to have that texture on just about any blank to contrast with the grind. It might also work as a way to get and artificial aged look with deep pitting. I thought by adding in some power it might be possible to get a deeper pitting on the surface in a shorter time and without removing the blade and cleaning the oxidation off. My worry is that it might not watch in a uniform way and just attack a single zone like I have often seen on boat's kept in a marina with someone who isn't well grounded. I wasn't thinking about a fancy colored anodized finish like on non ferrous metals. Just a way to make acids bite harder and have an interesting surface finish that might hold some color or even better form something like a mill scale.
 
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