Coffee etching??

[Kevin McGovern]

I was having a discussion with Jordan Lamothe at Ashokan over the weekend. He uses instant coffee and keeps it in the fridge to avoid spoilage. He stated it "held up pretty good" but that's far from a performance measure.

 

[weo]

I also keep my coffee in the fridge and it's lasted about a year now without spoiling. I've also found that the more I use it, it seems the better/darker/quicker it works (although the speed may be due to the fact that it's been summer). I've found that you have to shake the jug to mix it first, though.

 

[bmilleker]

How do these combination etches hold up to use? Although attractive, I find that ferric chloride is-not durable. I have started to just sandblast and stonewash, and skipping ferric chloride altogether.

 

[cicchis0]

This is a cool trick. I've never heard of it mixing the tea with vinegar before. I've heard of using green tea (among other things) as a rust converter in Japan, and it works nicely.

What I'm not getting is the silicone spray before putting the blade in the liquid... All he says is that it's important for getting a consistent black on the blade. But how exactly does putting a resist on the clean steel help this? I would think it would prevent the patina from setting.

Your thinking is correct but I think your spray identification is not. The English text visible on the can appears to say "Silicone Off". I don't know exactly what that product is but I'd expect it to contain some sort of aromatic hydrocarbon like toluene or xylene. I use a workshop/engine degreaser spray.

 

[Michael Black]

I've coffee etched several blades and I really like how they came out. I used tips/techniques learned from Mareko Maumasi and Neil Kamimura primarily.

Here is a sujihiki in 80CRV2

https://imgur.com/a/BOZjedH

Here is one in Damasteel:

https://imgur.com/cBvIjXK

Here is one in san mai with a 52100 core:

https://imgur.com/a/IdPTyQS

and a customer pic of the same knife after about a year of use:

https://imgur.com/a/oIf7MhY

On all of these I initially etched it in ferric (muriatic for the Damasteel) to get some texture in the etch, then followed it up in a fresh (extremely strong) batch of instant coffee for several hours. Then coming out of the coffee etch I use compressed air to dry it without touching the blade, lightly applied a coat of wax to the blade and hit it with a heat gun and hand buffed with a clean cotton rag. The hot wax finish really locks in the coffee etch, otherwise it does tend to wipe off easily, like Stacy mentioned. I have found the wax to be a remarkably durable finish at least in a home kitchen use. I've been using that sujihiki pretty much daily since I made it over the summer and the finish hasn't changed at all, although to be fair it just gets used on meat, so it is pretty light use.

Mareko also talked in a recent Knife Talk podcast too about how he has had better luck with super clean relatively low grit (400) finishes for coffee etches, as opposed to the high grit finish you would normally use with ferric.