Sulfuric Acid Etch?

fitzo said:
Gene, I'm sorry I'm not going to be much help; it's been since 1972 since I've used NitAl for etching metals. Thinking about it, I seem to remember we made it fresh daily in the lab and chucked it at night. If you store it, use a glass bottle rather than plastic.
Read this Wikipedia article. It is good info. I would stick to using methanol (wood alcohol) if you can find it. DON'T try it with acetone.
You might get good input on best etching concentration and further advice e-mailing Kevin Cashen. He uses it to etch metallographic samples. cashenblades.com
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I used 2% nital to etch steel micros, I mixed nitric and reagent grade ethanol,works great for metallographic etching of steel micros, it is not a damascus etchant, stick to Ferric Chloride.

-Page
 
I hope you will let us know how your experiments work out, Gene.

You may find that the concentrations of nitric acid necessary to accomplish damascus etching are high enough that it would be better and safer to simply dilute the HNO3 with distilled water rather than alcohol. The Spanish "strong water engraver," Antonio Montejano, does highly detailed acid etchings on knives using HNO3 (aqua fortis, ie, "strong water"), so it can certainly be done. How well it will do differentiating steels in etching damascus can only be discovered through experimentation.

I wouldn't be discouraged from trying it the way Mike was scared off of trying the sulfuric acid. Just experiment safely. Personal protective equipment, ventilation, and easy access to water to dilute any "excursions".
 
It should work, but needs to be very diluted. Just for fun I put a knife in strong sulfuric acid and it dissolved the entire knife in an hour.

For cleaning strong stains on our steel instruments, we mix hydrochloric and nitric acid and dip the steel in briefly. Too long would just dissolve the steel.
 
sunshadow said:
Oh since we are talking about acids
NEVER EVER PLAY WITH USE OR OR HANDLE HYDROFLOURIC ACID unless you really know what you are doing AND have calcium gluconate within easy reach. We use it as an ingredient in some of our metallographic etches at work and it is scary stuff. it goes straight through meat and attacks bone, it also attacks the calcium channels in nerve cells

-Page
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Some refineries use huge volumes of pure HF Acid in their process. I made it a personnel rule to never enter an HF unit a long time ago. The refinery I am currently working in has one and I told my employer right away I would not enter it. I am not a coward, I have opened lines and let gallons of liquid propane pour out around me, I have watched high concentrate sulfuric acid smoke as it burned the concrete beside me as I worked on the line gooned up in a rubber suit while breathing thru a compressed air hose. I know how I am and a pin hole in a glove might not stop me from finishing a job. This stuff is very nasty. A guy I worked with for years was missing most of a finger. Pin hole in a glove in a HF unit at the wrong time. Said it was like getting stung by a 50 lb bumble bee. Took a little while to get proper treatment and said they were actually talking about taking his hand off. This stuff is evil and has no place in anyone's shop. Breathing it in any concentration is a death sentence.
 
;)

i think you'll find that for PW that ferric chloride is very good and will little drawbacks... just degrease the blade well and away you go..

just as Mike has said... diluted nitric with distilled is good ( weak like vinegar ) but not as nice on PW ...sort of grayish in color... but in my opinion very good for etching quenchlines..... and good for etching crucible steels..
- i believe the alcohol is there most for a drying agent... if you don't becareful with this etch and dry it quick, it'll get a brown or orangish hue ( sorta rusty) which is unsightly..

dilute sulphuric is so so... alot of trouble to get anything nice with carbon steel... if you heat the solution it does tend to act as a stronger acid and cuts better... .. still, nowhere's close to as nice as ferric... and requires alot of fussing around


G
 
Stacy E. Apelt - Bladesmith said:
Some more basic info from another old chemist:

All acids are to be respected. The only way to make one safer to use is to dilute it. Vinegar is a dilution of acetic acid. Your stomach is full of diluted hydrochloric acid. Diluted acids are safer...but not safe. Proper storage and disposal are a must.

Some acids are more reactive with iron than others. The more reactive the ion is (chlorine, sulfur, etc) the more the acid eats at the steel. Steel with lots of acid resistant alloy ingredients (stainless steels) will require stronger acids and longer times.

Storing strong acids inside is an invitation to corrosion. Acids are best kept away from anything you don't want rust on. A locked and ventilated storage shed is best. Most acids can be diluted to harmless solution and dumped down the drain. Concentrated acids need a dilution of several hundred times to be safe for the drain system. Neutralization should be done only by those who understand it.

Ferric Chloride is what you get by combining iron and hydrochloric acid ( HCL). Muriatic acid is HCL. Sulphuric acid is a strong acid, but reacts with steel slower. White vinegar ( a dilution of glacial acetic acid) will etch slowly and is safer to the hands.

Acids for etching work best in dilution. Muriatic acid can be diluted about 5:1 with water and makes a much more handleable acid. Always add the acid to the water....never the other way around!
FC works better in a 3:1 to 5:1 solution. When mixing acids with water, especially dry ( powdered) acids (like FC) great heat can be created. Use a safe and proper container, sitting on the ground/floor. Add the acid slowly, and let it sit after dissolving until the container returns to room temp. Never hold a container in your hand and mix chemicals ! Mix dry FC with water on a 1#FC to 1 pint water ratio to make the stock solution. Dilute this as desired. I usually go a bit weaker, and add 5# FC to a gallon of water for my stock solution. This I dilute from 1:1 to 3:1 for use.

Stacy
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I went through the post to see if it was asked following but I didn't see anything.

I see the dilution rates for FC and HCL, but what would the dilution ratio be on Sulfuric Acid? I'm looking to Etch my blade and I have a box of it from a Battery Fill kit that wasn't used.

Thanks in advance
 
My advice is to leave the H2SO4 alone and get or mix some FC.

Just because you found an old pack of scalpel blades, don't make it a good idea to do brain surgery with them.
 
BoricuaForge said:
I went through the post to see if it was asked following but I didn't see anything.

I see the dilution rates for FC and HCL, but what would the dilution ratio be on Sulfuric Acid? I'm looking to Etch my blade and I have a box of it from a Battery Fill kit that wasn't used.

Thanks in advance
Click to expand...

A note of caution regarding diluting acids: the rule in the lab is "always add acid to water while stirring." Never add water to concentrated acid. It'll splatter on you.
 
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