so what's the best acid to use to get a deep etch design in tempered steel? in mild? Thanks

Ferric chloride is the one I hear used most often; should be available from radio shack for PCB etching.

I've used muriatic acid and a mask to get a design before, think I got the acid from tractor supply. Tbh though I have a burning hatred for and fear of strong acids so I usually opt for the safer/easier option - electro etching!

I think that what you use would best be settled by what you intend to do, though; are you masking a design and etching it or something else? The mask I used with the muriatic acid didn't do well and the text came out rather blobby. But it was runes on a viking sword, so it wound up inadvertently looking like a welded iron inlay...

I would go for Nitric acid. Altough it is evil, and super strong, leaves abeautyful and fine trace on the steel. I recommend to use a solution of 10 percent, since it is much slower. After the process, clean the surface carfully! And one more thing. Do this outside, if not, everything in Your surrounding will be rusty!!! I have already worked with this solution, and I am pleased with it. GIve it a go with ferric chlorid too, it is not as expensive, and said to result in beautyful, deep black colored etching, it is quite pupular in revealing the damascus steel's pattern. Just a little hint: When You are making the protecive wax cover, use bees wax, than heat it over a candle, so it turns black. On this surface You can make Your drawings much more easyily, since You know, what exactly are You doing! :)

Good luck!

John

I use Nitric acid too, diluted to about 15%; too strong and the reaction can run away if the etch area starts overheating. I use a soft and cheap brush to whisk off any bigger bubbles that form, which can leave a rough edge - throw the brush away at the end. I also use a tilt table to slosh the acid in a horizontal bath to sluice away bubbles as they form, it gives a cleaner and/or deeper etch. At the end, I wash the piece under running water, then neutralise any remaining acid with dilute sodium hydroxide (NaOH) - if you don't do this the item will rust 10 times faster than usual. I usually use laser-cut vinyl transfers as a mask, if you give them a day for the solvents to dry out they stick well as long as you don't scrub the surface.

Also, experiment to get your process sorted BEFORE doing it on a valuable piece that has a lot of time invested in it - there is no going back with etching!

I would vote for the Nitric acid (HNO3) etching also.

As I'm fond of old traditions and technologies, I use tar/gasolene solution to mask the areas and strong (about 30%) acid. Although the process was shown in the "Yushman Project" thread, it could be hard to find it, so I'll show how I do this again.

* the tar/gasolene solution is applied by hand or through a cardboard pattern

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** after the tar dries off, the excesive tar is removed with great care

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*** the plates in the plastic vessel, filled with the acid

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**** and the result - after the etching the plates are MANDATORY washed under running water, then neutralized (already mentioned by Peter Lyon sodium hydroxide gives good results; I could recommend the simple but effective Sodium bicarbonate NaHCO3 also)

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Beautiful work, Boris.

I will agree with using Ferric Chloride or Nitric acid for submersion etching. which to use may be a matter of which steel you are using, as they react and color a bit differently to various alloys. Try both on scrap pieces to determine color, depth, and control. I would also suggest diluting the Ferric Chloride as well. If you are using the Radio shack PCB etchant, try 3:1 and 4:1 water to etchant.

For small areas, or if a tank will not be suitable for you, there are other options. I have used pickling pastes designed to clean oxides off welds. These pastes are meant to stick to the work while etching, and are used in many places where welds are made in the field. I generally keep 4 pastes from AvestaPolarit in my shop for different uses. They tend to be low fuming, so there is less chance of everything in your shop rusting just by being close. For carbon steels, I recommend either their 101 (white) or their Greenone 120. Blueone 130 and Redone 140 will probably blur the edges, as they work better on stainless and high nickel steels.

I'm about to commission a blade to be laser-etched. The etcher is looking into seeing if a blade will fit in his machine, but, I'll post results if they come out nice.

Murphy :cool: