Coffee Treating Damascus Blades


Chef Knife by Mareko, treated with a coffee solution to etch the blade for the final finish


Coffee Treatment by Mareko Maumasi

Note from Caleb:
Mareko Maumasi of Maumasi Fire Arts is a bladesmith who specializes in high end kitchen knives. Aside from being easily in the top kitchen bladesmiths at work, he is also extremely passionate about sharing his experience, knowledge, and experiments.

Typically he posts weekly videos on one or another damascus pattern, however a little while ago he did a detailed series of videos on his Instagram profile on a method he uses to finish damascus: the Coffee Treatment. I asked for permission to transcribe it to text, as I find this very useful to save and study for later. This is the full transcribed version with only minor edits: if you're looking to get all you can, I recommend reading this article. You can watch the original video series here. For simplicity, I also rewrote the information into a shorter article that hits the main points and troubleshooting tips. That will be part two. 

Transcription from video series by Mareko Maumasi.

"Today I wanna talk about coffee treating blades, I'm not gonna be doing a pattern this week. I get a lot of people asking me a lot of questions about "what is this coffee treatment you're doing?" "Why are you using coffee instead of just doing ferric?" And so I want to answer those questions, help you trouble shoot it as well because I've been working on this technique for finishing my blades for the last two years I've been messing with it. I have been getting consistent results here and there but then something changes and I don't know what it is. And it's only been the last month that I feel like I've really nailed a system for doing this that works really well and gets consistent results. "

"Okay so right off the bat I want to talk about mixture ratios and temperatures. 
Like I said I've been playing with this process the last couple years and temperature plays a big role. Essentially, there's a whole spectrum; the colder the mixture is, the slower it etches. Which is good, because overall the coffee is a pretty mild acid that is affecting the steel, and so once you get to the hotter end of the spectrum, like boiling hot water, it can etch a blade, it can get the results you're looking for in maybe like ten minutes. Versus on the cold end of the spectrum you can leave a knife in there for 24 hours."

"So I use three cups of one of these seven ounce containers of nescafe clasico dark roast, with half a gallon of water. "

"So now let's talk about prepping the blade before you actually get it into the coffee. I use ferric chloride, which is usually like a 4:1 ratio water to ferric chloric acid which is also still a pretty mild acid; you can get it on your hands and go wash them later and it's not that big of a deal. Definitely don't wanna get it in your eyes and don't wanna ingest it. But anyways I use ferric chloride to etch my steel down to the depth that I want. From there, once I have the depth that I want in my steel and the pattern I take a spent, worn out 2500 grit piece of sandpaper and scrub the whole blade down. This is after neutralizing: I use baking soda water to neutralize the blade, and do a wet sand on it. "

"And then, especially if the blade is off the handle material, you're good to go. You don't have to paint on any resists to protect any kind of handle material or anything, you can just go straight in and start hanging your steel in the coffee. If you do, like I typically have my handle attached to the knife as I'm etching it into that acid, or rather dropping it into that coffee. If I don't have a resist painted on, (like I'm talking like a nail polish painted on; clear nail hardening nail polish. Essentially it blocks the coffee from coming into contact with my handle material) it will stain it, as well as it's unnessecary extra moisture that would be getting on the wood so you want to do something like that to protect your wood."

"So that is in preperation to getting your knife ready to dip into the coffee mixture. Now like I said, there's a huge spectrum from cold to hot that all works, but the mixture ratio, how much mix you're doing, how hot is it, how did you prepare your blade,  it's pretty much three major factors that I've been fussing around with for the last two years and like I said it's only been like in the last month or so that I feel like I've really figured out something that's 1, simple and user friendly and safe, and 2, gets very consistent results; the last two knives that I've posted on my instagram, I've used this technique for both of my knives."

"So I mix my three cups, this is a seven ounce container, essentially three cups, three measuring cups, of instant coffee, mix that into half a gallon of water, then I bring that up to like a simmer almost, so some of the water is starting to steam. I don't bring it up all the way to a boil anymore: I used to, but I don't any more. Essentially I want to bring it up to what I call "tap hot"; whatever the hottest temperature that your tap water gets. You can still put your hand under there unless it's around 180 degrees, before it feels like it's burning your hand. But for most people's homes, you can put your hand under your hot tap water that's been running for the last couple minutes, at its full temperature, and you're good to go. You can even use your hot tap water to mix with your coffee and pretty much get your knife straight in there. Once you have your mixture ratio, you've got your temp, you get your knife in there, and you want to hang it in there, I check it every ten minutes. I've done all kinds of stuff like I said, but I've been finding recently that checking in on it every ten minutes has helped a good time period. You don't want to let it go too long cause maybe it's not etching evenly and getting the results that you want. Anyways, every ten minutes until it has the darkness you want. The last one I did, it took forty minutes, which sounds like a long time but for the results you get it's well worth it." 

"Okay, let's talk about some troubleshooting. I've had all types of messed up stuff happen and think that I'm doing the exact same thing that I did last time and it's all going to s*** and it's not working, so for this new process that I'm doing, after the first ten minutes I go in and I take a look at the blade. If it's not darkening evenly, there's something up with the preperation you did with the blade. So what I do is I pull it out, and I scrub the blade (I don't neutralize it or anything) down with a (I think it's a) 4/0 steel wool, a very very mild abrasive, but that helps break everything down, even everything out, and then I put it back in the coffee."

"That should do the trick. If that happens like 2-3 rounds down the road, it's okay, it can be frustrating, do the same thing, put it back in the coffee, come back, check it every ten minutes. That happened actually, two knives ago that I posted, I'd already been etching the knife for like thirty minutes, I thought it was going great; I pull it out, and it looks like s***. And I think "y'know what, I'm just gonna try this.", so I took the steel wool, scrubbed it all down, put it back in, after a couple more rounds, it was perfect. So, don't freak out, be calm. That's the other trouble shooting suggestion I have for you."

"Sometimes, if you don't have an even amount of dark material in your damascus and bright material, essentially silver and black lines (the 15n20 is typically the silver line stuff), if you have too much bright stuff it probably won't etch very nice and easily in fact it'll probably darken, and I'm not entirely sure why that is, it just does, and it doesn't really look that great and so maybe in that case the coffee treatment isn't necessarily the best route for that blade or that pattern style or whatever. I don't know if this process works for stainless steel; I've done very very little with stainless damascus so that is something for somebody else to discover, not me."

"Okay, just to recap now. You wanna take three cups (at least, this is what I do), for my process take three cups, or a seven ounce container of nescafe classico dark roast instant coffee, to half a gallon (or two liters of water), bring it up to tap hot, either by using hot tap water or by heating it up on your stove and pouring it into some sort of container (I use a 3" diameter PVC tube with a cap on it), you put your coffee in there, and then hang your blade (if you have to prep your blade, use a resistor or something to keep the coffee from staining your handle material), and then check it, every ten minutes until you have the color you want."

"Final thing, is once you do have the color you want, take it out, neutralize it in baking soda water, wipe it down with a paper towel. Only a little of the black will wipe off onto the paper towel but even after wiping the blade down, it should still look great. If it didn't do that, you wanna hit it with that steel wool again, go back for another couple rounds, until you have a solid black that doesn't wipe off with a paper towel, and then from that point, dry it off, you're gonna oil your blade, if you use a rennaissance wax, use a rennaissance wax, but, you should be done at that point. For me, etching the blade is like the second or third to last thing I do because after that, I take photos, after that, I sharpen it, after that, I send it on its way."

"So, in closing, the coffee treatment does work. The reason I like it, is it's coffee. It's food safe. And it gets really nice high contrast results. There are a lot of ways to get nice high contrast results, I don't know exactly what anybody else is doing, I just know that this works for me and I like that it's food safe. If you try this, it works for you, great. If you come up with something else that works, I would love to hear about it. The biggest reason I'm putting this out there, a lot of people are "Don't tell the secret, don't tell this stuff!", the reality is like, I want there to be progress in the trade, in the craft, and I want people to put out great stuff! Put out stuff that they're proud of and not because it's just what they could achieve. And when I say achieve, I mean I've been making knives for a while, for the last 4 1/2 years, going on 5 years on my own there have been plenty of times where I could not get the finish on the knife that I wanted and I was like "you know what, **** it, I'm just gonna buff the whole thing!" 
But that doesn't feel good. So the reason I want to share this is because it's something that works for me, it's very user friendly, it's safe; I was doing a lot of stuff with buffing wheels before and that can be really scary and dangerous (people have died from it)."

"Basically, I just want people to feel proud of the work that they're doing, that they're putting out there, and I don't want them to feel limited because of their lack of knowledge. Ultimately, you can either do this work or you can't. And a lot of people have (and this gets into some muddy water a little bit), in my philosophy I hear a lot of people talk a lot about "training your competition, competition, competition, competition, gotta keep your secrets, competition!". I don't believe there is any competition so I have no problem, and that sounds like it's a very egotistical thing, and that belief comes from the demand for finely crafted, well made knives, far far far exceeds the supply."

"And because the demand far exceeds the supply, that means that there are hundreds of thousands of people all around the world who want well made knives. I can make them for them, I know plenty of great makers out there (I'm constantly talking about other makers), who possibly are a better suited maker for a particular person. That's totally cool with me because there are enough people out there interested in the work for every talented knifemaker to make knives for. So I have no issue putting any of this kind of stuff out. 
Sorry about the little rant, I want people to put out knives that they feel proud of. I would love to see your results if you give this a go, I would love to hear feedback. If anybody has any questions please do not hesitate to reach out to me, I'll do my best to answer any questions you might have and follow up. The system that I've come up with, that I'm using now myself, it's pretty straighforward. Hot water, instant coffee, scrub down the blade, put the blade in the coffee, let it do its thing, check it every ten minutes. Once it's dark, and it's durable, and it's holding its finish, you're good. So, have fun, be safe. Happy holidays!"

I am actually going to be travelling west back to washington for the holidays, I'm not gonna be in the shop so I'm gonna be doing things a little differently. If people have any questions, I would love to hear them. I thought something that I could try to do, is try to help people with stuff they're working on and processes they're struggling with whenever. One of the things I've really come to appreciate working in a shop with other makers is that you have people to bounce ideas off of and I know that there are a lot of makers out there who work by themselves. I was one of those people until about six months ago. And so, if you have questions, ask! Because we can work together to figure things out, bounce ideas off each other, and to help break through whatever kinds of barriers and walls you might have. Alright, take care!


Caleb Harris

I’ve always fooled around with tools and hardware, but I think my passion with blades started far back in my childhood: wooden swordfights with the neighborhood kids. I became the neighborhood “blacksmith”, using my grandfather’s tools to hammer little crossguards onto wooden sticks. I always tried to find the best scrap wood: lightest, strongest, trying to get the perfect length and shape for each “customer”. This started my passion with blades.
When I was ten years old, I joined a local rock and gem club, learning stonecutting and cabbing, and through that came to take silversmithing lessons from a local jeweler. It wasn’t until around the age of 13, that I turned my attention to bladesmithing, which has captured my heart. 
 My personal obsession with bladesmithing, as I’m sure you can relate, isn’t just the joy and passion of the making: the musical clang of the hammer on steel, the shower of sparks on the grinder, the whisk of the blade over the sharpening stone, but also of the fulfillment in creating something that is twofold: that of beauty, and that of function. It’s trying to make something that is as much an art piece, as a tool that you can trust your life with. That’s what caught my heart, and the pursuit of that perfect combination still drives me.