What is the best material to resist muriatic acid?

REK Knives

REK Knives

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Knifemaker / Craftsman / Service Provider
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Need something that won't allow "bleeding" when soaking a blade in hot muriatic acid (160f). I've been using a paint enamel marker but it breaks down after a couple of minutes and I have to remove, clean, and reapply. Gets really old!
 
12345678910 said:
Try nail polish
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Thanks, I used to use nail polish before switching to the paint enamel but would still have issues although I have read all nail polish isn't the same... So if you have a specific recommendation then I'll snag some from Amazon! :)
 
I usually have good results from the cheap obnoxious fluorescent colors...and as always, good surface prep (degreasing) is key.

~Chip
 
I've seen markers used for designing circuit boards. No idea if that would hold up to muriatic acid but as most of the solution is water and markers tend to resist water, dissolve with organic solvents, which HCl/Muriatic isn't, it could be okay.

Didn't save the time tag, at about 0:35 they pull out the marker and then the rest is pretty much them drawing and dipping and then around the 3:15 mark you have the final result.
 
bflying said:
Yeah, sounds counterintuitive when I say it out loud also. Not being a chemist, was curious. Like how some acids can eat right through metal, but store just fine in a plastic bottle.
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Reactivity, metals are dissolved by the ions of the acid, somewhat similar to how rust works, but plastic is impervious to most acids. It isn't too different than how plastic is used as an insulator in wires while the metal wire conducts electricity. Acids are essentially strong positively charge ions in solution, the H+ being the acidic part in HCl/Muriatic acid. OH- is generally the negative alternative in aqueous (water based) solutions.
 
Also, consider lowering the temperature of the acid. It will still etch, just slower. Hot acid is usually used to etch whole surfaces, not masked off surfaces.

One thing you might try is High Temp porcelain/enamel paint for stoves and such. For small jobs, the touch-up bottles should work.
 
razor-edge-knives said:
Need something that won't allow "bleeding" when soaking a blade in hot muriatic acid (160f). I've been using a paint enamel marker but it breaks down after a couple of minutes and I have to remove, clean, and reapply. Gets really old!
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CA glue ?
 
I would try dielectric red insulating varnish. High adhesion up to 300+ degrees.
 
Why does the acid have to be so warm? Keeping it room temp would take a little longer, but it would certainly expand your options, I would think.
 
Drew Riley said:
Why does the acid have to be so warm? Keeping it room temp would take a little longer, but it would certainly expand your options, I would think.
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Yeah it comes down to speed, I could lower it a bit but I don't want to go all the way to room temp as that would take a while to get a deep etch on damasteel. I'm not sure if that would even help or not without experimenting. But I have 15 blades or so to etch so the quicker the better
 
razor-edge-knives said:
Yeah it comes down to speed, I could lower it a bit but I don't want to go all the way to room temp as that would take a while to get a deep etch on damasteel. I'm not sure if that would even help or not without experimenting. But I have 15 blades or so to etch so the quicker the better
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I wondered why the high temp also. You mght just be looking here at a fundamental trade off between time vs quality (not uncommon... )

At a lower temperature the etching reaction will be much more predictable, and you will have FAR more options for resist (aspaltum/beeswax being the classic i guess). You could also possibly go with a photoresist if you need that level of quality. Agitation will help speed things up at lower temperature (and improve uniformilty). Best results (uniformity of etch) will be had at lower temperatures and continuous agitation) (i can explain the why behind that statement if you wish...)
 
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