Etching Damascus With Muriatic?

Michael J. Spangler

Michael J. Spangler

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Oct 8, 2003
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hey guys, i used the lovely search function with pretty much no results.

what are your opinions on using muriatic acid to etch? should i dilute it with distilled water?

anything i should know before i dip a knife into it? thanks a ton guys
 

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Michael, my advise would be to dilute it down subtantially with distilled water. (Add the acid to the water, not water to acid, for safety reasons.) Start very dilute, like 1:10 or 1:20. Add more acid if necessary.

The more concentrated the acid is, the more likely it is to "attack" both steels equally. You want to get a good "differential" rate of reaction to the acid. Dilute will do that better.
 
Michael,
The general "rule" is to etch steel mixtures containing nickel with ferric chloride, and those without in muriatic.

John
 
interesting, what's the science behind that?

thanks Michael. i was planning on calling you but i figured i'd do a post. once i screw it up a few times i'll call for the low down on it:D
 
Michael,
As I understand it, the ferric doesn't attack nickel the way HCl does, allowing you to get a deep etch on the non-nickel steel, and a polish on the N. I use 15n20 and 1084, and ferric at 4:1 , H2O to Radio Shack liquid ferric. I often use HCl to burn out scale pre-welding, and it does hit the nickel pretty hard.As for SCIENCE...

John
 
The "active ingredient" in ferric chloride solution is hydrochloric acid. Here is a little discussion of the chemistry; the pertinent part is what happens when ferric chloride is dissolved in water. It is in a greatly reduced concentration compared to the 30% hydrochloric acid (muriatic acid). That is why I recommended you dilute the HCl way down with water, Michael.
When someone feels their ferric chloride batch has "gone bad", you can add a tablespoon or so of muriatic acid and regenerate it.
 
fitzo said:
The "active ingredient" in ferric chloride solution is hydrochloric acid. Ferric chloride is dissolved in water. It is in a greatly reduced concentration compared to the 30% hydrochloric acid (muriatic acid). .
Click to expand...
OK Mike (Fitzo) Both are hydrochloric acid diluted to different %'s/levels/proportions??? Dliuted Muriatic = Ferric ??.
Some mason's left 2 gal of muriatic acid at my house after an additon was finished. I can "make"
what I need for etching out of Muriatic Acid?!?
For the chemistry ignorant why did you warn him about which to add to which??
 
Tom, diluting muriatic doesn't make ferric chloride, no. Dissolve enough iron in it...yes. :) The chemistry of what goes on in ferric chloride etching versus only hydrochloric acid is a bit more complex, but it is still driven by the acidity. Check out that link and, where it says, "copper", realize there is stuff going on with the iron that is vaguely similar.

Regarding the order of addition: there is heat generated at the interface between the water and acid when you pour one on the other. If you pour water on acid, it generates a lot more energy than the other way around. It can actually boil in a small area and cause splashing of concentrated acid in unwelcome places like our face.

I apologize that my ability to explain chemistry in layman's terms is not very good. Teachers have a special gift for communication that I've really come to appreciate.:o
 
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nice, this rocks good info

though i didn't have luck with the muriatic. i went 10:1 water to acid with a 20% hydrochloric muriatic acid, didn't work out that well.

i found it to be blotchy and it didn't really etch much of the surface.

so i used the tiny little bit of ferric with some fresh distilled water and used a smaller container to lay the blade in, it worked out pretty good. i'll have to mess with the muriatic again sometime.

i did cold blue the blade and lityly sanded the higher material to make the lighter material really pop. it looks pretty cool. when the cameras batteries charge i'll have to post it.

thanks again guys!

mike what are your suggestions for the solid ferric?
 
I know at least one ABS Mastersmith that used muriatic acid to etch then blue their blades...he doesn't much care for Floric Chloride...it isn't deep enough.

Craig
 
Michael, it's easier to add more acid and try again than make it too strong and over-etch. :)

Regarding the solid ferric chloride: the liquid from Radio Shack is about 35% FC. If you dilute it 1 part RS FC plus 3 parts water (1:4) you have around 9% FC. So, you could either take 350 grams and dissolve in dissolve water until the total volume is 1 liter to make the equivalent of the RS FC, or add bout 100grams to a liter of distilled water to get in the same ballpark as diluted stuff.

When you dissolve the solid, be aware that it will form hydrochloric acid gas, so do it outside, and keep it downwind of you. It will also generate heat, so add the solid a little at a time, stir to dissolve, then add a bit more. Do it in glass, not plastic, so you don't have an accident melting the plastic. Leave it set a day or so before use. There should be a precipitate form (ferric hydroxide). Let this settle down to the bottom then decant the liquid to another container just like you do with wine. The cooled liquid can now be stored in plastic, of course.

Hope that helps.
 
The best thing about Muriatic acid is that it comes in a two gallon box for about $7 at Home Depot. The worst thing about Muriatic acid is storing two gallons of it without eating up every piece of steel in the shop.
Stacy
 
Guys, can I ask an added question here? I recently gave this a shot with undiluted muratic acid. The Damascus under up looking like I spilled bleach on it....zero contrast. What did I do wrong to get that result and how should I have done it?
 
Welcome Chitwode.
This is a thread from 2008. Lok at the dates of previous posts before resurrecting an old thread. Only Fitzo and I are still here (and we are both getting old).

Without knowing some of the details it is hard to know what happened.
What was the steel?
How long was it etched?
Where did you get the muriatic acid?
Was the blade completely sanded and cleaned before the etch?

Here are some suggestions:
1) Use diluted muriatic acid at about 10:1
2) Use ferric Chloride instead of muriatic acid
3) Sand blade completely clean of decarb ab-[nd wash to remove all oils and such before etching.
 
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