Quick acid etch question. . .

A

atomicjoe23

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Mar 1, 2011
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Posting this up here because this sub-forum seems to do the most acid-etching. . .

. . .will the PCB etchant from RadioShack etch thru the mill scale on steel or does the scale need to be removed so there isn't an oxide layer blocking the ferric choloride?

I'm not etching a knife. . .I'm etching some mild steel plate for some decorative work I'm doing; this is the first time I've tried the acid-etch so I'm trying out on a small 3" square piece of scrap first. I'm also trying out something I've seen done on car paint jobs as well. . .I sprinkled water on the steel before I spray painted and let the water bead up, then I spray painted the metal with the water droplets on it so the paint won't adhere to the steel where the water droplets are. . .after the paint dries wipe of the paint that didn't adhere and allow the acid to etch in a random pattern to created an aged look to the metal.

Thanks for the help!
 
I think the scale should be removed. If nothing else the etching would be uneven with the scale left on.
 
I would scale should be removed and I use hydrochloric (muriatic) acid to do my etching. Cheaper and faster. It can be bought at pool supply stores and home depot.
 
Thanks for the input. . .I just went out and checked on the progress (with the scale left on). . .after about 2.5 hours there is some etching happening, but not very much.

I will try again tomorrow on the other side with the scale removed and on a second scrap piece with the muriatic acid. . .I appreciate the suggestion.

On a side note, for what I'm doing I'm looking for a random and uneven etch. . .on want the steel to look naturally aged so an uneven etch is fine as long as it doesn't take forever.

I'll update with progress pic's of tonights experiment tomorrow afternoon and the follow-up experiment on Thursday (then it's off for a weekend of razor clamming!).
 
Oh yeah, I wanted to put out a little thing I tried out tonight as well. . .

. . .due to the size of some of the pieces I'm working with finding a flat, shallow plastic enclosure large enough for the pieces has been a challenge so I decided to improvise a little and make a cofferdam for each part rather than placing the parts in a container.

I used some gutter sealant (you know. . .the stuff in the caulking tube, clear silicone I believe) and I made a cofferdame around the edges of the part and poured the acid in. . .after 2.5 hours there is no leakage and it looks like the silicone is impervious to the effects of the ferric chloride. . .I'll have to see about the muriatic acid, but this will require the use of a LOT less acid and being able to do a large part all at once' plus it will give me a very irregular line for my outline (something I want) without the effort of cutting stickers out with an Xacto knife.
 
I think the ferric chloride will remove the mill scale if left in contact long enough; i know it will remove the heat treat scale. Any kind of oil or grease residue will resist the etch so be sure and clean the metal well (Dawn dish soap, break clean, carb cleaner). I dilute the Fe3Cl 4:1 with water, etch 1 minute, rinse, rub with 0000 steel wool to remove the oxides, and repeat until I get the look I'm after. Of course, that's on a blade sanded to 800 grit or finer. You'll just have to play with etch times to see what you get.

hope this helps

randy

PS I wouldn't use acetone as a degreaser either; it seems to leave a residue that causes streaking in the etch.
 
Hmmm. . .after leaving the FeCl on the steel (with the mill scale left on) overnight the FeCl did remove the mill scale, but that's about it. . .that's without changing the acid out at all. . .

. . .I took two more 3" squares of 1020 and removed the mill scale with an angle grinder and one of those blue sponge style discs. . .sprinkled them with water, sprayed the paint on, put the silicone around the edges and just poured FeCl (straight. . .not diluted) on one and muriatic acid (once again straight) on the other.

Gonna let them soak over night and see what that gets me. . .

update tomorrow.
 
On average how long does it take to get a decent etch?

I'm not necessarily looking for a super deep etch, but I do want it to be noticeable. . .

. . .I'm hoping that I don't need to change the acid out a bunch of times to get an etch.

Thanks for the help so far!
 
"allow the acid to etch in a random pattern to created an aged look to the metal."

Do a search for "mustard etch" or "forced patina"
 
I'm familiar with that John. . .not sure if it will work for the appearance I'm shooting for though; the mustard patina is just a discoloration while the acid etching actually removes material which is what I would like to do. . .

. . .I'm trying to simulate ancient viking stuff. . .not remake it, but like you dug it out of the ground after quite a while
 
Ya know. . .this is turning out to be a "not so quick question about acid etching". . .I must be doing something wrong. . .

. . .I checked my test pieces yesterday after work (which means the acid had been on them for just short of 24 hours) and all I can say is "EPIC FAIL"!!!

The PCB etchant hadn't done anything to it's test piece (this was with the mill scale removed) and all the muriatic acid did was remove the paint and make the test piece nice and shiny (once again I removed the mill scale before applying the paint and acid)???

One of the guys I work with is bringing me a bottle of TapOut (basically nitric acid, but I don't know the percentage) and I know that will work, but I don't think it will be enough to do all the stuff I need to do. . .I found some Tap-X chemical tap remover, but I haven't checked the MSDS sheet yet to see if it's nitric acid or something else yet. . .I would have preferred to work with something a bit milder than nitric acid, but if that's what I gotta do, that's what I gotta do.

I'm just surprised that I didn't get any etching effect at all. . .I wonder what I'm doing (or not doing) that is causing this not to work? When I read through the CS Tomahawk Mod thread it seemed pretty easy and fool proof( not sure what that says about me).

Anyone have any suggestions?

M3mphis. . .thanks for the links, read the first one and getting ready to peruse the second right now. . .
 
My etching experience extends only to knives, and so far I'm not very good at it :o. I have learned a few things though. Splattering nail polish or wax on the steel seems to work well for producing a random, organic pattern, but using resists like those gives you clean lines and a stark contrast between the etched parts and the shiny untouched ones. It looks purposeful rather than aged. I have found that a full surface etch (with no resist, just clean the metal and put the acid on it) followed by stonewashing produces a very cool "aged" look. I havent' tried water and paint before. I have also tried cutting gorilla tape to create specific shapes, but the acid always seems to get under the edge of the tape in at least a couple small spots.

As for your problems getting the steel to etch, I haven't had trouble with that yet. So far it seems to me that less corrosion resistant steels (like blades) etch much faster and darker, and more corrosion resistant stuff (handle scales and clips) etch slower and don't darken as much. Maybe you have a very corrosion resistant steel? Or perhaps there is some oil or some other resist on the surface of the metal? I clean and degrease all surfaces before etching. You are using new acid right? I use PCB, and after etching a bunch of stuff it has turned a dark color and seems to be working much more slowly.

How deep are you trying to etch the metal? The depth of the etch I get is largely dependent on how long I allow parts to sit in the acid. Just 10 minutes will discolor a blade on all places exposed to the acid, but it's just the surface. I can't tell that it actually removed metal. But if I leave a handle scale immersed for, say, an hour and a half, I can feel the edge between the protected areas and the etched areas. It feels textured, as if the acid removed a few thousands of an inch. The color doesn't change any after the first few minutes though. The steel will quickly reach it's etched color and will not darken further.

All of this may or may not be helpful, but that's all I got. I'm still experimenting :D. Good luck dude.
 
Thanks strick284. . .

. . .the steel is just hot rolled 1020 mild steel so it's definitely not corrosion resistant. . .I didn't necessarily degrease it, I just hit with a an angle grinder using one of those blue scuff pads to remove the mill scale. . .

The PCB I just opened the day before yesterday and it was very dark right out of the bottle.

I've got some nitric/sulfuric acid now that I'm gonna try when I get back from the weekend (and I will be using safety glasses, gloves, apron, and face mask. . .worked with the stuff back when I was in the Navy and I don't want to get it on me ever again!).
 
So far. . .

. . .PCB solution = fail. . .muriatic acid = fail. . .Tap Out (nitric acid/sulfuric acid/acetic acid solution) = fail. . .

. . .I cleaned the metal each time, the muriatic acid was brand new from the store that day; the PCB solution was a couple of months old, but I hadn't opened the bottle previously so the seal was broken seconds before I used it; the TapOut was REALLY old (from the 80's) but once again the seal had never been broken and was opened seconds before I used it. . .

. . .wondering why this isn't working? The only thing I can think of is the low carbon content of my steel (1020 HR). . .or the solutions are too weak.

I'm thinking of ordering a bottle of nitric acid and a bottle of ferric chloride and trying it in a much stronger solution to see if that will work.

Any suggestions on why I'm not having any luck?
 
atomicjoe23 said:
So far. . .

. . .PCB solution = fail. . .muriatic acid = fail. . .Tap Out (nitric acid/sulfuric acid/acetic acid solution) = fail. . .

. . .I cleaned the metal each time, the muriatic acid was brand new from the store that day; the PCB solution was a couple of months old, but I hadn't opened the bottle previously so the seal was broken seconds before I used it; the TapOut was REALLY old (from the 80's) but once again the seal had never been broken and was opened seconds before I used it. . .

. . .wondering why this isn't working? The only thing I can think of is the low carbon content of my steel (1020 HR). . .or the solutions are too weak.

I'm thinking of ordering a bottle of nitric acid and a bottle of ferric chloride and trying it in a much stronger solution to see if that will work.

Any suggestions on why I'm not having any luck?
Click to expand...
Bingo Joe you hit the nail on the head with the carbon content,i bet your 1020 is just a drab colored gray.And BTW you should have all of the scale removed and a nice even scractch pattern from sanding to get a good etch.Ferric Chloride attacks carbon and is what causes it to etch black,while muratic will only give you a dull gray
 
So am I pretty much SOL as far as an acid etch goes on the 1020???

I made sure to clean all the mill scale off after experimenting with it left on once. . .all the acid did was eat the scale off. . .
 
atomicjoe23 said:
So am I pretty much SOL as far as an acid etch goes on the 1020???

I made sure to clean all the mill scale off after experimenting with it left on once. . .all the acid did was eat the scale off. . .
Click to expand...

You should still get a grey patina with muratic,but that's only going to be skin deep
 
I was hoping for a textured appearance on the metal. . .

. . .what I'm trying to achieve is a deeply aged appearance for the metal.

This is for a door and bar hardware for a local brewery. . .their Viking-themed so everything is raw wood, heavy steel, with accents of sisal/hemp wrapping and copper and brass accents where I can work them in.

Thanks for the help so far. . .
 
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