Issues with ferric chloride and acidwashed/darkened finishes

LCKT707

LCKT707

Joined
Feb 26, 2015
Messages
576
I've watched a lot of videos and read peoples tutorials on this plenty in the past. My approach has essentially been what they say, soak until desired color, use ammonia to stop process, clean, then oil. I've had these issues in the past and with persistence and extra washes and tumbling sessions I've somehow gotten past them. But they just came back with a vengeance and instead of just neanderthaling through it I'm looking for a reason why it's actually happening and how I can avoid it.

For those who don't use FC for darkened finishes; this is the finish I'm trying to achieve. A lightly tumbled acidwashed finish to hide scratches from use a bit and to give it a rustic sort of look.

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Some people like it, some people don't. That's fine! But lately either it's my acid going bad or something else happening that is keeping me from achieving an even finish. I clean the entire blades before their bath and then wipe them with acetone to remove any oils. I then hang the blades in a 100% FC mixture by string/wire/whatever else I can find. I give it a couple dunks and swirls initially and let it sit for a couple minutes. I pull it out, check the darkness, leave it back in, sometimes rinse it off with windex and then water before giving it another bath. I do this until the desired level of darkness is achieved.

However now I am getting this; immovable and unchangeable crud finish when I rinse. Certain spots darken while others just seem to plain refuse.

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Now that is A2 steel mind you... it usually darkens extremely fast where as the others I've shown and work on are usually stainless AEBL, 20CV, S35, etc. So I am basically at a loss here for what is happening. In the past I'd tumbled a blade like that for a bit, clean it thoroughly, then give it another bath in Ferric Chloride. This would alleviate the problem. Right now it seems nothing is getting this blade an even darkened etch.

Is 100% FC not a viable mix? Do I need an agitator of some sort? Does it need to be scrubbed evenly while in the FC? Is it because I don't have an abrasive blasted finish prior? Has my acid gone bad?

I'm open to any suggestions besides "don't use that finish" lol because that's what people are ordering. As funny as it is :)

Appreciate any help or responses!

Ryan
LCKT
 
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1) The ferric chloride is too strong. When I etch damascus I like a 4/1 or 5/1 ratio of water to ferric. Remove the blade every 5-10 minutes for cleaning and then back in the acid. This process shows details in damascus and leaves an even etch.

2) Finish the blades to a higher grit to have a more even surface for etching.

3) What your tumble media? Could it be leaving residue preventing an even etch?

4) Replace your ferric and clean your etching container to see if you get different results.

Chuck
 
Alpha Knife Supply said:
1) The ferric chloride is too strong. When I etch damascus I like a 4/1 or 5/1 ratio of water to ferric. Remove the blade every 5-10 minutes for cleaning and then back in the acid. This process shows details in damascus and leaves an even etch.

2) Finish the blades to a higher grit to have a more even surface for etching.

3) What your tumble media? Could it be leaving residue preventing an even etch?

4) Replace your ferric and clean your etching container to see if you get different results.

Chuck
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Chuck thanks for the response! My tumbling media is a god awful mix including medium grit triangle cut ceramic and straight rocks. I have some better media in my "cart" but cannot afford to order it yet. The kind I found that everyone has good luck with requires a large order. I typically thoroughly clean the blades before an etch even after tumbling. Soap/water with scrub, acetone, wipe and dry with fresh paper towel and then only touch with fresh nitrite gloves as to not leave any hand oils.

As for the mixture I usually had great luck with it; however I'm no chemist lol so there may be deeper reasoning for a lighter ratio I'm not understanding. I do know my desired etch is much darker than the average maker who uses damascus to see patterns. I have however recently read someone using a mix of FC and Vinegar and they get really good results. However they use an abrasive media blast prior to the etch or open the metals' pores. I'm going to order another gallon of FC and start using a diluted mixture and test different mixes. Including yours.

Honestly it seems like the acid may be old as you said; as it's probably 2+ years old and has etched about a hundred knives. I don't know the shelf life of that sort of thing outside of their original container.

I will use your advice in some of my troubleshooting methods thanks!
 
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WValtakis said:
How to get a better Etch. Acids and etching from a chemist

~Chip
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This is what I needed, Chip, thank you! This explains the deeper meaning behind diluted acids. It was my understanding 100% would be stronger but I felt I was missing something. This is why I failed school and turned to throwing sparks for income LOL. A lot of tutorials or how-tos are simply "dunk it in and check the darkness level". They lacked a lot of detail.

What would you say is the best container to etch blades in? A tank where they hang or like a Tupperware you can sit them in?
 
Hanging, anything touching it will affect the etch.:)

~Chip
 
Two other things:
Acetone should not be your final cleaning step. It leaves a residue on the blade. If you use acetone, wash the blade afterwards with warm water and dish soap. Put it directly into the etch without wiping, since a paper towel can leave fuzz on the knife.

It also looks like you may have dust contamination in your ferric. I was having this problem, and replacing the ferric chloride solved it.
 
Tenebr0s said:
Two other things:
Acetone should not be your final cleaning step. It leaves a residue on the blade. If you use acetone, wash the blade afterwards with warm water and dish soap. Put it directly into the etch without wiping, since a paper towel can leave fuzz on the knife.

It also looks like you may have dust contamination in your ferric. I was having this problem, and replacing the ferric chloride solved it.
Click to expand...

Thank you! I figured acetone would take any residue off and not leave any on as it evaporates. I tend to wipe it down with a clean shirt to get fuzzies off but I will move to soap and water. This is the third mention of my ferric so i'm definitely going to replace it lol. It is also possible due to the size of my shop and placement of the container that I am getting dust contamination over time. I'll have to look in to moving things around!
 
Pure acetone does not leave a residue unless you didn't thoroughly clean the part. That being said, not all acetone is the same. It is also not particularly great for you. I generally only use it for stuff that denatured alcohol won't dissolve. (Also, ethanol evaporates more slowly, giving you a lot more time to actually clean the part). But if you get a high quality pure acetone the only residue it will leave is stuff it disolved after it left the bottle. You have the same problem with any volatile solvent, acetone just evaporates more quickly.
 
That's interesting. I always see a film left behind. Maybe my acetone isn't pure -- or maybe it dissolves binders from the paper towel?
 
Tenebr0s said:
That's interesting. I always see a film left behind. Maybe my acetone isn't pure -- or maybe it dissolves binders from the paper towel?
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I generally use blue shop towels for cleaning crap, I haven't had any issues that I have noticed. I suspect it is purity. THe vapor pressure of acetone is very high at room temperature, meaning that in anything but a very confined space, acetone will evaporate VERY rapidly, anything left behind is not acetone, it is whatever else was dissolved within in. But also remember that unless you are rinsing, not just wiping, to a large degree you will just be removing a part of what is on the piece.

As I said, I generally prefer alcohol for most tasks, and if it is significantly greasy, I use degreaser or similar. I find windex generally works fine prior to etch as well.
 
With all the advice and help ya'll fixed my problem. Got a new container, new Ferric Chloride, distilled water and vinegar. Perfectly even etches and they're getting much darker than before! Even added a soak container for WD40 baths. Thanks everyone!
 
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