Etching stainless steel with Ferric Chloride

[GT_84]

Hello All,

I have some Ferric Chloride laying around from my previous work with PCB etching. So yesterday i came to know that Knifes can be etched too. I watched couple of video on YouTube and saw the patters on the knife and tried it on my stainless steel knife that i bought from a grocery store. Not taking care of the ratios of water to etching solution, i dipped it for a minute and the whole knife turned black. I pre-treated it by cleaning with soap water and then with isopropyl alcohol. Should i had to heat treat it or maybe sand it ? to get a pattern. The patter i was after is not anything fancy or done with stickers.

Is there pattern that form naturally after heat treating ? Heating it to red hot and then quenching it into  cooking oil ?

Would appreciate some help with the pattern and etching.

[GT_84]

Attached here is the knife.

[Frazer]

If the blade is only one type of steel then it's only going to etch one color. Generally speaking people etch pattern welded steels that are made of 2 or more alloys that etch differently. 1095 (which etches dark) and 15N20 (the nickle content causes this alloy to resist the etch and stay bright) are common examples.

The hardness will also make a difference. For reasons unknown to me hardened steel etches darker than it's unhardened counterpart. You could try deferentially hardening/tempering the blade yourself, but some of the stainless alloys out there require more precision temperature control/soak times than I could accommodate in my shop. Without knowing the alloy and what process to follow you're more likely to ruin it than anything IMHO.

I think it would be easier to use a resist of some sort (nail polish might work) and do some sort of design on there. That could be splattering, or doodles or streaks or whatever you want. You could even do layers of that. Add some nail polish, etch for a minute, add some more, etch again, etc..

I've never done that besides when anodizing titanium, which is different in method, but conceptually similar. Maybe it could work here.

Ive also seen people etch with mustard and get patterns, but I don't know how well that would work on stainless.

 

P.S. Welcome aboard. There's really no reason to post something twice. We saw it, people will get back to you, patience is a virtue. If you haven't already, READ THIS.

[GT_84]

Thank  Frazer. That explains the natural patterns. So I want etch it completely black. what would be best. I am not a knife maker in anyway but i have a PVC tube, Ferric chloride, a heat and some cooking oil. Would heat treating make any pattern ?

[Frosty]

Welcome aboard GT_84, glad to have you. If put your general location in the header you'll have a chance of meeting up with members within visiting distance. Also PLEASE do NOT use the @ tag in posts it doesn't work as a tag and messes with the Iforge operating system making the mods remove it. if you're addressing someone use just their name or login. If you're replying to the post above, no need to use a name at all. Make sense?

Frosty The Lucky.

[Frosty]

Double posting is a B A D thing do it very often will get you moderated.

Frosty The Lucky.

[Frazer]

As I mentioned it may be possible to do with differential hardening/tempering. However, I wouldn't recommend that you try to reharden the knife unless you know what kind of stainless steel it is and that you can safely follow the procedure for that alloy.

If you just want black.... Isn't that what you already have after your first attempt..?

[GT_84]

Well the black turns to gray when cleaning it with a scotch brite. Should i reduce the concentration of the etchant ?

[Frazer]

That's very true and difficult to avoid. Rather than scotch bright I use a piece of worn out 2500 grit sand paper. If you go crazy with it you can still go too far. This isn't like a DLC coating where you get a true black and durability.

Try reetching, clean up with the worn 2500 grit, clean with windex (or some other streak free cleaner) and then soak for several hours (maybe even overnight) in SUPER concentrated instant coffee. I don't measure, but I put 5-7 heaping spoonfuls in a 16 oz cup of water. Cold water is fine, some say better.

I wonder (dare I say, doubt) if the steel will retain it's corrosion resistance when all is said and done. I wouldn't clean it in the dishwasher when you're done for fear of rust.

[GT_84]

So coffee retains the color. Would fade off when washing the knife after use or would it ever transfer to food ? like when cutting lemons, meat or vegies ?

[Frazer]

It doesn't retain it, but it does make it darker. Yes, the fading over time is pretty much inevitable in my experience. It may transfer to food, but assuming you clean it well after you're done I doubt you'll notice... Just don't take my word for it and give it as a gift or something without some testing of your own.

I've never done anything like this with stainless so YMMV.

[Steve Sells]

the pattern seen in SOME blades is from using multiple kinds of steels to forge weld the patterns into the steel, because different stels react differebtly to the acid,  the etching only shows what is already there. Mono steels wont show anything