When you rust blue, you coat the polished metal with an acid solution that creates a thin film of red rust(ferrous oxide) Then you boil the metal in distilled water for a few minutes. The ferrous oxide converts to ferro-ferric oxide which is black. The rust is removed with fine soft wire brushes and the process is repeated until the metal reaches the desired color, usually about 3-5 rusting cycles.
Randy
Sorry for the late reply and this may have already been mentioned, I just arrived here and may not have all the headers, anyways... For damascus I use a mixture of 1 part ferric chloride (availiable from Radio Shack for $3.99) and 3 parts water. I do 3 etchings, 15 minutes each, rinsing the debris from the steel with clean water each time. I hope this was on-topic, I missed the original post
BTW is there a FAQ for this group?
I've never done it but read about it enough times I can tell you got it right. (even tho I couldn't have postred it;) I used to be on the "knife-list" with Bob Engnath, DrH and Howard Clark.
FAQ's are to keep certain things from being repeated so much... no fear of that here! ;)
Alvin in AZ (hobby stock removal knife knut)
I've used battery acid, hydrochloric acid, and strong sulphuric acid, but I never trusted it. I've gotten more reliable results from a precise heat treatment routine. This does require a digital oven with a hold range of less than five degrees, but the result is more controlable than etches. Besides, I don't think that you can ever get ALL the etchant out of the steel once you expose it, and that's the engraved invitation to corrosion down the road. I get color shift and three-dimensionality, so why dip all this hard work in something that will dissolve flesh and bone, even if for only a few seconds?
Charly
How long? :)
That's for sure. :)
Is that a pun? :/
So I've go no experience with this but should'nt a neutralizer take care of any residual etchant?
GA
Most, but not ALL. When you etch with an acid, you wash with an alkaline. The problem is that most alkalines are cut with water to bring the concentration down and that pesky surface tension interferes with getting down into the intergranular spaces. This leaves traces of the acid buried down in the tiny spaces of the metal, waiting for moisture to reactivate it. Remember the Souix City DC-10 crash? That was brought down by a sandgrain sized crystaline discontinuity in the fan wheel of the center engine. It doesn't take very much at all to start corrosion, and it grows in the dark till one day..... crack. This is especially bad in steel, as the oxide takes up more space than the metal and you get intergranular wedging that literally pushes the grains apart. In pattern welds, this can cause delamination and structural failure. I can do without that, I sweat too hard for this stuff as it is.
Charly
It varies with the alloys. The idea is to sweat a little of the carbon out of the high carbon parts that are exposed to deflate the surface a few thousandths to give the 'feel', then polish the high parts which are already decarboned to reveal the pattern. This works quite well with cable, as well as hi-lo carbon steel laminar. It's not as effective with chrome or nickel alloys, as it's the carbon we're working on.
Not intentionally, the mind plays tricks on you at 0 dark thirty before the first pot of coffee soaks in.
Charly
concentration
Cool. I've noticed that there are a lot of folks out there using etch to pattern or bring out the pattern on their blades. I seen etching done on (homgenous?) non forge welded steels and forge welded alike as an extrememly common practice. Can you still get the color gradients without etching on the forge welded materials?
GA
Unless you're using some 'exotic' like nickel or chrome, the color shift is the difference in carbon content. Low carbon will be lighter, high carbon darker. This is especially evident in cable, as the 'surface' of the wire strands decarbons during welding, leaving a high carbon core. When you cut into this during machining, you expose the cores of the strands, and the color shift..
Lots of folks use acids because they're cheaper and quicker than precision heat treatment. Time is money. But after a few years in the aviation field, you get a healthy respect for the effects of corrosion in metals, and you want some other way to achieve the effect. The procedure I use took months of experiment to get down pat, and a lot of scrap metal was produced on the way. Mask etching is another matter entirely, and is strictly decorative. I notice that most mask etches are done on homogenous stock.
Charly
Battery acid, hydrocloric, aqua regia, and lots of others that I HAVE tried will eat your flesh bones and cloths... not ferric chloride, I dont even use gloves when I handle it and I still have about 70% of my flesh remaining. Seriously its safe to handle. Doing it the way I described allows you to etch as little or as deep as you wish, just rinse and neuralize (I use baking soda to clean between etches and a liquid neutralizer when done) Try it on a piece of scrap and you will see how simple and safe it is to etch to just a color change or to whatever depth ya want.
First of all, Ferric Chloride is not a safe baby play chemical. It is a solution of HCL (read that as Hydrochloric or Pool Acid...) and HCL that has been forced (yea right) to react with iron. What it does is the FeCl reacts to copper since copper is a lower 'oxidation' state metal it is replaced by the iron (Fe). The Fe on a pcb isn't glued to the glass board. It falls off into the tank. The copper is attached to the Chlorine CuCl (in rough terms) and goes out of action (unless Al is introduced). Along with all of this is FeCL and HCL. So with steel one is etching with the HCL floating in the Ferric Chloride. That is why it isn't so strong - more FeCl by plan.
I'd use rubber or chem gloves myself. It does etch the skin. It stains a rust yellow brown on the skin until the next new growth. In the 30's the finger prints were burnt off the hands with either HCL or (less used) Nitric.
The FeCl is a moderator of sorts. The solution can be fortified with HCL or pool acid remembering to add acid to the mixture. Warning: The mistake of so many is to add water to acid which creates a steam bubble that explodes acid over the user/adder of water.
I own a lab coat that is splashed orange when a pyrex tray split during heating. Un-even heat.
Martin
On Sat, 23 Oct 2004 02:05:14 GMT, "Martin H. Eastburn" wrote:
Snipped the crap
yellow brown
If you use rubber gloves, how do you know it etches skin, turns them brown? Did you just read that, or talk to someone who tried it, and actually experienced that while etching damascus?
heating. Un-even heat.
Oh... you own a lab coat! Dont I feel just a tad silly, all I wear when I make damascus is a leather apron over my clothes. How does that lab coat do with hot flux? heh Listen up, wear gloves, helmet, respirator, and your lab coat all under a hazmat suit... anything that makes ya happy, I could care less, in fact if I was at your shop and saw you handling ferric chloride with gloves Im sure it would just make my day. Did you happen to read where you can buy this "nasty" stuff? Radio Shack! Do you think they require every geek who makes a circuit board sign a waiver, or even read a msds? And I just LOVE your warning about adding water to acid! Did you just read that? Isnt that like 7th grade science? And now you would like to pass that knowledge on? Just so I can be safe, next time I gear up with lab coat, gloves, grounded wrist-strap in place, standing on an anti-static mat, CAREFULLY open the hood to my truck, with a plastic no-spark battery cap removal tool, look into my batteries at a safe distance, using a mirror, find that the electrolyte level is low, should I remove my truck batteries, dump the contents into water, then dump the whole mess back into the battery, just to be safe? OUCH! Im sorry, my yellow brown, acid burned fingers are in such agonizing pain I just ... can t... t yp e n o m o r e. Oh and dont foget about the: if you can smell it, you breathed it, and if you breath it, it mixes with the moisture in your lungs and once that happens... And finally, I just looked it up for you, so you have some real info to "read" (mind you this is from folks who think everything is harmful in some way)
"Acute Health Effects: From MSDS: EFFECTS AND HAZARDS INHALATION (BREATHING): Inhalation of concentrated mist or vapor may cause irritation of the respiratory tract. EYE CONTACT: Contact with eyes may cause irritation and tearing and eye tissue discoloration, and may result in permanent visual loss unless removed quickly by thorough irrigation with water. SKIN CONTACT: The product is an irritant. Contact may include irritation with dryness, discomfort or rash. Ferric chloride has been infrequently associated with skin sensitization in humans. Extensive exposure could lead to skin ulceration. Severity is generally determined by the concentration and temperature of the solution and duration of exposure. INGESTION (SWALLOWING): Ingestion may cause severe liver and/or kidney damage, and may be fatal." For a MSDS thats pretty tame. You want to be scared, read this one:
a rust yellow brown
steam bubble that
heating. Un-even heat.
C'mon man, show a little charity. Some folks are just genetically predisposed to react badly to their environment and need more protection then the rest of us.
GA
haha I'll tell ya a bad reaction- reading your reply with a mouthful of hot coffee :) (now I need to find a rag thats not all eaten up!)
a rust yellow brown
steam bubble that
heating. Un-even heat.
Is it really necessary to be so harsh to someone who is only expressing concern for your well being? There seems to be developing on this group to many caustic responses that belittle someone for expressing an opinion or asking a question. Many of the people who used to post here no longer express an opinion and in some cases I am sure it is to avoid ridicule. If you cannot express an opinion in a reasoned manner, and preferably with some knowledge behind it maybe you should go back to your parents to learn some manners, and consideration for your equals and in some cases betters. YELLING DOWN OPPOSITION OLNLY DISPLAYS YOUR OWN IGNORANCE.
rust yellow brown
bubble that
heating. Un-even heat.
I can only guess you can't read or understand well. I don't use a lab coat when pounding metal or welding or such. I'll use it around the lathe or mill.
It got splashed when doing a demo to an advanced class I was the professor for. It was getting educated types into another branch of life - PCB's. We were into black tape and blue and red tape. Those days.
You need to understand that a 7th grader isn't allowed around danger stuff. Now read the MSDS - Skin sensitization - means your feeling is changed in your fingers. If you don't like changing your responses to bran senses - go ahead. Dryness, Discomfort or Rash - not friends of mine - means something is going wrong. Skin ulceration - wow - boils and ulcer from just having it on my finger - NO WAY!
Etch your metal away - not your fingers. This is not weak stuff.
As a test, put about a cup of FeCl into a glass container - that can handle heat. Take it outdoors. Add - with tongs and with eye protection - a loose roll of Al foil.
Expect a very hot and foaming reaction - with spitting acid.
In this sense - be cautious on using Metals with Al or other light metals as they will etch out rapidly and might etch deep into layers.
Martin
When I first started out forging blades back in the early '80s I could not get an honest answer from anyone on how to make damascus. After many years, piles of worthless beat-to-death half welded pieces of metal, yards of burnt steel cable, I finally got it. Back then I was etching with everything from vinegar and Naval Jelly to Nitric Acid. I was working with a dragon's breath design forge I built for welding, a coal forge for shaping, vertical mill, burr king belt grinder, buffer, oxy-acetl torch. Of all that equipment, the most dangerous part of the entire process (IMHO) was the etching. You would not believe the safety measures I took to keep from breathing, touching, mixing, inserting and removing steel, and then to actually store it. This was truley nasty stuff, that would ruin a blade if you left it in for a minute too long. I still have one that is a shining example of how to make a skeleton etch. About 10 years ago, while at a master bladesmith's shop, we were playing with some combinations of metals, made some blades, and came time to check out the patterns with a quick etch. I could not beleive my eyes when I saw the ease of using ferric chloride. No exhaust hoods, no goggles, no going outside, not even any gloves! Welpf! Not to mention that it was so incredibly controllable. So now I had to find a way to dispose of the gallons of various nasty acids I had collected over the years. I managed to unload most of it to the local high school, the aqua regia was pretty much unwanted by anyone though and turned into just a major pain in the butt. So here is the bottom line: This is a blacksmithing group, the thread started by one other than myself concerned etching a pattern welded blade. Keeping that in mind, my reply is as follows - ferric cholride is safe and effective and easily neutralized. I base that not on something I read, heard, dreamed or imagined, but personal experience that I freely share with anyone who wants to know how to etch damascus. I guess I need to also say just how "I" do this in a way that is not harmful to "me". I have a bottle of ferric chloride mixed with water. I dump it into a plastic tray. I clean my hands. I clean the blade. Using forcepts so as not to touch the blade with my oily little fingers, I place it in the acid. I look at the clock. I open a beer/pop/coffee. After 15 minutes I reach into the acid with my bare fingers, pluck out the blade, dip it into a bucket of fresh water with some baking soda dissolved into it. I gently use my fingers for the intial scrubbing. I pull the blade out, usually grin with satisfaction at how the pattern is coming out. Clean the blade, repeat the process. After the second 15 minute etching I know about how much longer I want for the third. Somtimes just a few minutes, sometimes I do a forth etching. So what, my fingers were actually in the acid for maybe a few seconds, just to retrieve the blade. Bear in mind this thread is Etching pattern welded blade. Its not Skinny dipping in Acid: Safe-r-Stupid? Would I do that with aqua regia.. dont think so. Would I do it with just nitric acid? no way. But ferric chloride, the way I descibed, for etching baldes, sure and unlike the folks I talked to back in the '80s, Im not going to make it sound difficult and magical to do. There is a sign on my shop door that reads: Everything in this building is Sharp, Hot and Dangerous (including the owner) and I would guess that holds true for anyone doing this sort of thing. If a person had the ability to light a forge and play with hot metal enough to make a billet of damascus, shape it into a blade, all without burning himself too badly, or cutting himself too severely, he can probably use a ferric chloride etch pretty safely as well.
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