Electrochemical vs acid etching

Alex Topfer

Alex Topfer

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May 1, 2019
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718
i'm working on a replica Fairbairn-Sykes fighting knife, and i was considering having a go at some of the etching that was on the originals. they did the original with acid etching, but these days everyone seems to use electrochemical.
any thoughts on which is the best approach?
i already have ferric-chloride, and will have to order stencils either way.
i can also order a basic electrochemical etching machine (i know you can build them, but i'm not going to)

thanks
 
If you are referring to etching the makers mark, then electrochemical is the best way to go.

For etching the blade surface to darken it, either FC or Parkerizing are the best methods.
 
It depends on how you want your finished blade to look. Electrical etching produces pretty clean lines and is relatively easy to do. I have not used that method because I am a fan of acid etching.

Ferric Chloride does a nice job of etching but I do not believe it is the best choice for the nicest outcome. To my way of thinking, clean crisp lines and the color of the bottom of the etch make a difference. It is a question of how much trouble you want to go to to do your etch. The method i have employed involved the use of a lamp producing ultraviolet light, and a specially formulated resist that cures hard when exposed to the ultraviolet light. I have used Ferric Chloride but found that it is inferior to an etch using acid. Using acids can be a dangerous operation because of the corrosive nature of it. It can burn your skin if not used carefully. The acid I used was a mixture of Nitric and Hydrochloric acids. the same acid that dissolves gold. it is called Aqua Regia. A company called Cronite is a possible source of resist and etching materials. You might examine some of the Logos of early knife makers such as Loveless, Henry, Dowell, Pugh, Stone or Hueske to get an idea of the appearance of acid etched markings. It is not a cheap or easy process initially, but produces a superior etch in my opinion and would give it some consideration.
 
Probably something like these...
usmc-raider-knife-002_orig.jpg
 
It looks like you could do that the same way we do our maker’s marks, just with a bigger stencil and an etching machine.

There’s a knife maker that posts in the custom and handmade section that does designs on his blades with etching, it’s very impressive.
 
Stacy E. Apelt - Bladesmith said:
If you are referring to etching the makers mark, then electrochemical is the best way to go.

For etching the blade surface to darken it, either FC or Parkerizing are the best methods.
Click to expand...

Sorry, yes it's closer to a makers mark. The original ones look deeper than the photos WValtakis posted.
6637710_orig.jpg


It looks like the big question is if I can buy resists for acids easily. I'm happy to use dangerous chemicals, but electroetching seems easier to get the equipment
There's still time before I have to decide: I haven't ground the bevels yet, it may still become an oyster knife
 
The easiest resist for simple acid etching with FC is a Sharpie pen. Draw a simple design or lettering (as in the image) using the Sharpie. Let it dry and etch in FC. Ply with it on some scrap steel.

Other popular resists are:
Nail polish
model paint
lacquer
plastic electrical tape
Press on plastic lettering
Dry transfer lettering

Don Agee uses the dry transfer sheets to etch his mark into the butt of all his knives. After putting the letters and dagger on from the transfer sheets ( he makes te dagger from a "T"), he wraps electrical tape around the handle right up to the edge of the smooth sanded nickel or brass butt plate. He etches for a good length of time with the butt downward in a cup of FC, The gas bubbles get trapped on the surface and slowly crawl sideways to escape. This makes the reticulated look. He likes to stick a piece of mosaic rivet in the center to make the neat shield look. Sometimes he has me set a synthetic ruby in the center.
Don Agee Knife 004.JPG
 
robwil said:
The acid I used was a mixture of Nitric and Hydrochloric acids. the same acid that dissolves gold. it is called Aqua Regia.
Click to expand...
Aqua Regia seems like way overkill - why not just sulfuric acid (aka battery acid)? It does not need to be really concentrated - more dilute will still work, just take more time. I got drops of sulfuric on my skin pretty often: no really big deal: you feel a little sting. Rinse with water and no real harm (glacial acids give less leeway. Aqua regia is not too bad on skin - but is kind of a pain to source, and again if highly concentrated gives less leeway). Bases (like sodium hydroxide) are much nastier on skin than acids, as they just chew proteins). With reasonable precautions (ALWAYS WEAR GOGGLES AROUND ACIDS - not just glasses) and reasonable concentrations, i would not be concerned about etching with sulfuric. (But i likely wont - because i am a terrible freehand artist - premade stencils for me for makers mark. :-). . Etching damascus though, that is a different story .....

(Might help to put things in perspective if you look up thr PH of Coke (the cola). If you dont know this you will be surprised)
 
Doesn't nitric acid also give off noxious fumes?
The freehand art part is a complication, I'm not good at that either. I'll go try when I get home
 
Alex Topfer said:
Doesn't nitric acid also give off noxious fumes?
The freehand art part is a complication, I'm not good at that either. I'll go try when I get home
Click to expand...
Any acid you dont want to stand over and breath ...any acid will fume if you heat it - but in knife making you should have absolutely reason to heat acid. reasonable room ventilation is always a good idea ... organic chemicals (ie “solvents”) typically throw off much more vapors ... but it is not like acid vapors are somehow instantly incredibly dangerous. Irritating, yes ... but your body will warn you if you are exceeding some lmit. If you sense some irritation, get out, increase ventilation, etc. the one weird thing about nitric is that it turns your skin yellow ... but it is not permanent (i know that from experience) .

The one acid i would be EXTREMELY afraid of is hydrofluoric acid. It is both very active (chemically), AND it is toxic. It absorbs through the skin, eats downward through tissue, goes systemic, and directly interferes with biochemical processes that keep you living. A couple drops on the skin is all it takes. But that is the ONLY acid i am afraid of working with. There should be absolutely no reason at all to work with HF in knife making...
 
Wax works, but you have to be absolutely sure it is all removed from the metal for the acid to reach the surface. Wax has the tendency to leave a film behind. Asphaltum sort of chips away and leaves the surface cleaner.
 
Boye says (just re read) melt together equal weights of bees wax and asphaltum, let cool and harden, then rub on to warmed blade. All available at art supply stores. Seems simple enough to make?

Man, i wish i had a knack for drawing - when i first saw his examples of etched blades back in 1977, that is what hooked me on knife making...
 
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