Acid and Rust....

[Marc Cooper]

Hey All

I have heard horror stories about Muriatic Acid causing rust to tools in a garage. I have purposely stayed away from the stuff as I have some high-end milling and lathe equipment that I certainly don't want rusted. I even keep a humidifier running 24/7 to reduce the humidity as much as possible. (I do CA finishes on pens and that works better with low humidity.)

Does Ferric Chloride have the same rust causing effect? I have heard good things about 50/50 Ferric Chloride and Vinegar, but want to make sure it doesn't cause rust like Muriatic Acid.

Thanks all!

 

[Bill DeShivs]

I have had no problems with rusting and ferric chloride.
I used to keep a gallon of hydrochloric acid in my shop. Though the bottle was sealed, it rusted almost everything in there, and ate the aluminum fins out of my air conditioner evaporator. I keep it outside now, and the rusting has stopped.

 

[Cushing H.]

Yeah - the problem is that HCl is actually a gas, and what we call hydrochloric acid is actually that gas dissolved in water. Once dissolved though, it is easy for some un-dissolves and goes back into the gas phase. Pretty small molecule, so it gets by a lot of seals, and when it comes in contact with a surface it adsorbes to that surface and you have ... acid etch. Ferric chloride is actually a solid at room temp, so when dissloved in water, it will not come out as a gas.

(just for yucks - sulfuric acid is a liquid in its pure form (glacial sulfuric acid). Not as bad as HCL, not as good as ferric chloride in terms or vapors escaping)

 

[Stacy E. Apelt - Bladesmith]

When I was a research chemist we had a small warehouse we stored drums of chemicals in. One was a drum of tri-phosphorous penta-chloride. It ate tiny holes in its drum and made a white smoke looking cloud when it reacted with the moisture in the air. At first they thought there was a fire. After determining that there wasn't a fire, I removed the drum and neutralized the contents by slowly dripping it into running water away from all buildings. That warehouse had significant problems for years from rusting iron and corroding aluminum. Even stainless steel things had pits in them. It doesn't take much HCl in the air to react with steel or aluminum.

Muriatic acid should be stored away from stuff you want to keep.