I wrote this in a different thread, and I think it is useful to share it here again.

In my opinion there are two kinds of etching, to wash out (H2So4) and coloring(oxidize) steel( ferric chloride, gun blue and other natural etchants like coffee)vine gear and mustard are slow and have uneven and unreliable effects, coffee is the best.

Etching with coffee has a few benefits:

easy to get, to prepare and to dispose , no chemical handling and waste.No harm to health, no goggles and stupid latex gloves.

It also gives better colors and it is no problem to etch twice on already finished presentation pieces(no acid surface line)

no harm or damage and discoloration to natural handle materials( well, on snow white Ivory I dont know, haven't tried that yet, but I guess it is no problem, try with a sample)

I always take one sachet (minimum amount to buy)which contains 45 grams and mix it with 500ml  clean water.....approximately.

I do not recommend groundwater, take drinking water or distilled water which has less impurities, minerals and that stuff.

The water should have room temperature, about 25-30 Degree C, dont take hot water, it turns a lot of the acids into base.

compared to ferric chloride it works a little bit slower the first 10 minutes but then it shows much quicker clean colors, no black, orange or olive complexion/smear what sometimes comes with ferric chloride etching.

Another good thing is You cannot over etch so easy...You leave too long in Ferric chloride You get black pit holes, blisters, bubbles and other ugly signs of over etching.

A friend of mine forgot a blade in the coffee, remembered it 18 hours later, there was no remarkable damage to the blade surface, just the colors became antique-dirty and  changed into black and white instead of black, grey and white.To do some damage it must left in there more than 24 hours, I guess.....but I dont want to try that out, no need for that experience.

Very important for having a good etch is, You have to create a good surface. Coarse marks will always show up dark and disturbing.....

The knife shown is coffee etched, there are three components in the steel O7(grey), O2(black) and 75Ni8(white), Grit 1200, etching time about 20 minutes.

 

I am no coffee drinker but I like a good fresh, brewed coffee in the morning, ...but this instant stuff You should not drink.....too much acid.

 

Thanks for the info and beautiful knife! Have you any experience using it on non pattern welded steel ? Just wondering how it works for bringing out a hamon or getting a black patina similar to blueing.

On 6/10/2016 at 6:33 AM, Prevenge said:

Thanks for the info and beautiful knife! Have you any experience using it on non pattern welded steel ? Just wondering how it works for bringing out a hamon or getting a black patina similar to blueing.

Thanks for Your reply!....I tried coffee etching with mono steels and it seems to work ok on steels that have enough Mn,like O1....but cold blueing in general works better.

In my experience coffee works on hamons very well.

I threw a Nessmuk WIP blade into the coffee yesterday to see what would happen. This was originally a John Deere lawnmower blade, probably something like 5160. One side came out a nice even grey; the other had this funky tiger-stripey effect around the edges.

Well, that didnt turned out as dark as it should(?)...5160 has 0.6% carbon, after forging You have some carbon loss, maybe 04% remaining....that is too less carbon to make the blade really dark with coffee.like I already posted, You need a good amount of Mangan and/or more carbon.

 

Well, this wasn't really a serious test, more a "Hey, let's give this a try" kind of thing. I don't even know for sure what the alloy composition is for the blade, although given how well it hardened, I'm pretty sure there's more than 0.4% carbon.

DIDN'T you have someone hold your beer?  <sheesh> What did you expect?

Frosty The Lucky.

Daddy always warned me never to drink and patinate.

No, I think he said not to drink THE patinate.

I wonder how making instant coffee with a % of vinegar would work?

Frosty The Lucky.

 

I agree, coffee is great for etching, and (for me) the best is, it is holding up far better i could have imagined. I am not good enough yet making my own knives without help, but I hope I will be sometimes. So I used the etching to build up a grey "patina" on the very sensible outer part of my blades of my bought kitchen knives. They have a core of so called "blue paper steel", outside there is an unknown steel, corroding within minutes if you let the knife lie wet after cutting and don't care wiping it dry.

The patina I built up that way is there now more than a year although the knife gets a lot of use and washing (no dishwasher of course). I used no instant, just usual filter-coffee, little bit stronger than I like it for drinking.

I'm at work now and have no access to my pictures while reading this part of ifi, so I will add a picture later.

To answer frosty's question: I believe, one could mix acidic (food-)components with interesting results, because there are people using mustard (there's vinegar), onions, ans so on, to force a patina on fast corroding steels.
Blood is used also, especially warm, to get a blue patina. The colour, one get's, differs with the steel as well  as with the patinate.

 

I've used dropped acorns/leaves from the oak trees at work.  Was shooting for a tanning solution for a hide & it stained the SS vessel pretty good.  Patinates most carbon steels in a few hours, and your hands, dishtowels, floor, etc.

grabs my coffee beans and hides them from you heathens...

using some freeze dried swill for etching is fine, but stay away from my fresh ground $50 a lbs coffee or there'll be fighting words spoken...

I take my coffee VERY seriously.

Next time I'm in Wisconsin I'm stopping by your place for a cup! I love good coffee we just can't afford it.

Frosty The Lucky.

On 6/18/2016 at 3:44 PM, firefly said:

The patina I built up that way is there now more than a year although the knife gets a lot of use and washing (no dishwasher of course). I used no instant, just usual filter-coffee, little bit stronger than I like it for drinking.

Do you have the knife still in use? Can you give a long time feedback on the coffee etching? 

On 12/19/2020 at 6:39 PM, Bad_Rockk said:

Do you have the knife still in use? Can you give a long time feedback on the coffee etching?

Sorry Sir, for the delay, haven't been there for a while...

The knife is still in everyday-use and the "shield" is still there and of great help. Never had a problem with "bad rust". It's a nakiri mainly for vegetables, and all I do is taking care as one should with every reactive steel. (That means rinsing immediately after use and drying, not giving away in wet condition for example...)  --- and honing of course, from time to time --

 

best, firefly

On 6/12/2016 at 8:55 AM, JHCC said:

I threw a Nessmuk WIP blade into the coffee yesterday to see what would happen. This was originally a John Deere lawnmower blade, probably something like 5160. One side came out a nice even grey; the other had this funky tiger-stripey effect around the edges.

Its all about even sanding even the stuff that we cant really see. Or maybe a blemish in the steel from john deer. Sand that baby down to 800 going with the grain of the steel. Id also try blueing if your going for darkness or just wait for the carbonation from the heat treat, just netflix and sand.

Also i like to soak in motor oil overnight after and etch to help with the dullness.