Does Acid Washing Damage the Integrity of the Knife?

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ShepardCC

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I have seen some of the acid washing done to blades, liners, etc using Muriatic Acid and I wanted to know if this damages the integrity of the knife??

Does anyone have any pics of just the knife being acid washed? or does everyone stone wash after?

Thank you in advance for your time and help
 
ShepardCC said:
I have seen some of the acid washing done to blades, liners, etc using Muriatic Acid and I wanted to know if this damages the integrity of the knife??

Does anyone have any pics of just the knife being acid washed? or does everyone stone wash after?

Thank you in advance for your time and help
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Im not sure about Muriatic Acid, I see most makers using PCB etching solution (ferric chloride IIRC) and it wouldn't damaged the integrity of the blade unless it was left in the solution for awhile. I see most makers leaving the blade in for 5-10 minutes and it essentially patinas the blade.
 
Nah.... unless you leave it in there for about two weeks. Not that I've ever done that.
 
It may make it more susceptible to rust, I'm not sure. Never tested that, but other than that I haven't seen any issues with my pcb washed blades.
 
The only reason it would cause problems with the steel is if it's left on indefinitely, or poorly cleaned so that acid is left in the nooks and crannies. Any steel treated with an acid should be neutralized to stop the reaction. Simple as scrubbing it gently with some paste made of baking soda and water, sort of like you would do to clean nasty battery terminals (but you don't need to be that aggressive), then rinse well, and dry.

If there are any synthetics on the knife (including handle materials, bushings, adhesives etc.), that might be a problem. Whenever possible, disassemble the knife so only the steel parts are subjected to the acid.
 
james terrio said:
The only reason it would cause problems with the steel is if it's left on indefinitely, or poorly cleaned so that acid is left in the nooks and crannies. Any steel treated with an acid should be neutralized to stop the reaction. Simple as scrubbing it gently with some paste made of baking soda and water, sort of like you would do to clean nasty battery terminals (but you don't need to be that aggressive), then rinse well, and dry.

If there are any synthetics on the knife (including handle materials, bushings, adhesives etc.), that might be a problem. Whenever possible, disassemble the knife so only the steel parts are subjected to the acid.
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Very good point.

You must be very careful with what exactly you treat. I considered doing the backspacer on my 810 Contego, but (luckily) consulted with Benchmade first. That part is made from powder steel. Not a good candidate for pcb. Also it probably would have dissolved the adhesive that held the carbide glass breaker in, not that I was too worried about that, but the point is that you need to consider every part that will come in contact with your solution.
 
Muriatic Acid. I want to make some scales for my 560 & 561. I know that when I do I may nick the liner. So I wanted to make one look like it came out of fallout 3. So I want a nice dark aged looks with like dark greys and bronzes.

I was thinking maybe duck tape and nail polish
 
If it were me I would just pony up the 12 bucks (or whatever) for the big bottle of pcb at radio shack though. It's a proven method. I haven't seen it done with muriatic before, not that that means anything.

Also, why just the edges? I'd do the whole liner.
 
From all the research I did those two acids were the ones used. Although the pcb was more for acid etching rather than giving it a dark color. Idk I may be wrong. But I took the safer route and bought the muriatic acid. Ill try it on a broken spyderco pocket clip first.

Why just the edges, because Zt already stone washed it and its dark but once I knick it it will show fresh shiny metal

I love Fallout 3. I played it twice. Over 600 hrs into it. Best Fallout game ever IMHO
I wish Bethseda would quit messing around and make the 4th one. But they have their one game per system rule! (They broke it for skyrim because the next gen systems where still 3 yrs away.)
 
Hydrogen embrittlement is a potential problem with some acids in contact with alloy steels. Hydrochloric/muriatic is one of them. http://www.omegaresearchinc.com/Publications/getpub.cfm?pub_id=5 Short story, not usually a big deal as the trapped hydrogen naturally leaves the steel after a few hours as long as it's not coated with a gas impermeable coating. Hydrogen atoms should be small enough that any baked on coating should prevent embrittlement due to the baking process after an acid pre-treatment. Parkerizing has enough iron in solution that there shouldn't be a problem as well. Using chlorinated lubricants/cleaning agents in highly stressed steels in moist environments, not a good idea.
 
So don't use muriatic acid??

I was plaining on cleaning it with a baking soda solution to stop the acid after I got the color I wanted.
 
ShepardCC said:
So don't use muriatic acid??

I was plaining on cleaning it with a baking soda solution to stop the acid after I got the color I wanted.
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Go ahead, just don't try to pry a paint can lid off for a few hours after you pickle it. The hydrogen soaks into the steel matrix and needs a while to outgas before it's back to full strength. It's probably academic given the pickling times and thicknesses and stresses involved with knives.
 
A properly executed etch should help with rust and will not damage the steel.


Clean your parts like crazy and remember that an etch will make scratches stand out more. 400 grit is the minimum finish I would etch at.

Use three parts water to one part pcb etchant, be careful as the fumes are bad and it stains everything... eats through some gloves so hang your part from some stainless wire or something.

Hot white vinegar does a great etch on most steels without the hassle of buying/storing ferric chloride solution.

A drop of dish soap in your solution helps keep the finish even.

I'd do a 45 second etch and see the results... no need for long soaks.

Windex works great as a neutralizer. Leave your knives for a few days after the etch; keep them soaked in oil or wd40 to be sure your etchant is neutralized fully.

Finish with a quick stonewash, 15 minutes is plenty.
 
Daniel Fairly Knives said:
A properly executed etch should help with rust and will not damage the steel.


Clean your parts like crazy and remember that an etch will make scratches stand out more. 400 grit is the minimum finish I would etch at.

Use three parts water to one part pcb etchant, be careful as the fumes are bad and it stains everything... eats through some gloves so hang your part from some stainless wire or something.

Hot white vinegar does a great etch on most steels without the hassle of buying/storing ferric chloride solution.

A drop of dish soap in your solution helps keep the finish even.

I'd do a 45 second etch and see the results... no need for long soaks.

Windex works great as a neutralizer. Leave your knives for a few days after the etch; keep them soaked in oil or wd40 to be sure your etchant is neutralized fully.

Finish with a quick stonewash, 15 minutes is plenty.
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All of that sounds exactly right to me. Vinegar for carbon steel blades though.

Daniel, do you get a darker etch from treating more than once? I've tried a few times, but I can't seem to get my finish much darker than the initial treatment. I wash very well (scrub) in between.

Thanks, op I hope you don't mind me butting in. :)
 
Another source of acid is the Works toilet cleaner, it's hydrochloric acid based, cheap, and the slight clingyness makes it easier to work with than just straight acid.
 
Strigamort said:
All of that sounds exactly right to me. Vinegar for carbon steel blades though.

Daniel, do you get a darker etch from treating more than once? I've tried a few times, but I can't seem to get my finish much darker than the initial treatment. I wash very well (scrub) in between.

Thanks, op I hope you don't mind me butting in. :)
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Yes vinegar for high carbon and tool steels, I don't have any experience etching true stainless steels.

I do get a darker etch from multiple treatments but results seem to vary. Boiling or very hot water works well to set the etch.

I hope this helps!

OK back on topic! :D
 
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