Thread: Damascus steel etching question

To make the lines visible on a Damascus steel blade does anyone know the percentage strength (% w/v) the ferric chloride needs to be?

I use a 35% solution. Most makers will cut that even further with distilled water. I estimate the Radio Shack 16oz bottles to be about 35% but that's only my estimate. Radio Shack doesn't publish much probably for proprietary reasons. Most will cut that with water 1:3 or 1:4. You can find similar copper etch solutions at art stores, they are ferric chloride too. Sometimes you can get lucky and find the dried crystals and make your own.

Thank you, Mike Blue. I did find some dried crystals on amazon but didn't know the desired mixing strength. I appreciate the input.

I made my mix a long time ago by dissolving iron sponges in hydrochloric acid. Every once in a while i add acid or a sponge. Haven't a clue about the strength

The same calculation should hold true for the dried crystals by weight dissolved in water. 65% weight of water, 35% weight of crystal.

Bruno is correct about dissolving iron in hydrochloric acid (found as muriatic acid for cleaning concrete). This reaction produces ferric chloride. Corporate chemistry houses will "recharge" ferric chloride by adding hydrochloric acid to the mix. Occasionally pouring off the natant and cleaning out the crud at the bottom of the container is about all I did for many years of use. Then a dash of new acid and an old rusty nail. It's kinda like keeping a sourdough recipe...but needs less attention.

As an aside: be careful when cleaning concrete this way. Back when I was young and naïve, I was working a summer job where the foreman gave me a coupld gallon of muriatic acid and told me to clean the concrete film from the floor, using that and a mop. I figured that if he said it would be ok, it would be ok. Not too long into the job, a thin stream of blood started running out of my nose. I had to go to the doctor to stop it, and every winter when the air is dry I still get nosebleeds.

I think that I went with a 2-1 mixture of distilled water and the Radio Shack stuff. I don't etch super deep like some folks do and that mix gives me that nice "chatoyance" on higher layer count stuff.

Hmm, chatoyance is a concept and visible feature that has not been discussed here before. I'd like to know what you think. Is it only the etch that produces this phenomena? Can it be enhanced in other ways? Probably for those who have never seen it, other examples would be very helpful. Do you have some?

Mike, layer count seems to be the BIG factor. In my limited experience, the chosen pattern is a close second. Ladder pattern of 180 layers looks good, but going to at least 300 layers REALLY seems to just make everything pop even with a relatively shallow etch like you might do on a kitchen knife. I try to go to around 400 layers on bigger blades. I can even get tet effect without going to a crazy fine 2000 grit plus finish. it will work at 800-1000. I am sure that having a steel like the O2 that Bruno and other guys from the other side of the pond are able to get will help because they get REALLY dark with all of that manganese and makes for super contrast. I have also seen some guys do some tricks like a final "etch" in instant coffee to get the non-nickle bearing steel even darker. i don't have any good pictures as I am a lousy photographer, but i will see if I can dig some up. I finally have time to get back in the shop and it is getting cool enough to forge, so i am gong to try a high layer count western kamisori style blade in the near future. i am really interested to see what, if anything different the deep hollow grind of a straight might do to the look of the pattern.

Originally Posted by Mike Blue

Hmm, chatoyance is a concept and visible feature that has not been discussed here before. I'd like to know what you think. Is it only the etch that produces this phenomena? Can it be enhanced in other ways? Probably for those who have never seen it, other examples would be very helpful. Do you have some?

Originally Posted by Learner

To make the lines visible on a Damascus steel blade does anyone know the percentage strength (% w/v) the ferric chloride needs to be?

An alternative answer to your question is that there are a number of weak acids that you can use other than ferric if you have trouble finding it. Vinegar, lemon juice and some others have been used. I have heard that heated vinegar works better or at least faster than cold. You just have to play around with the stuff. I have also heard some people say that diluted ferric, will give you a better looking etch that the straight stuff. It will take longer though.