Old Etching solution

Oregon has "neighborhood hazardous waste days". They show up at a school parking lot and accept residential quantities of stuff for safe disposal/recycle. They thank me for accurate labels on all the nasty stuff I take and have never refused to take anything.

If you use ferric chloride as etchant you can reactivate it by adding HCl (hydrochloric acid). You never have to dispose it until you want to get rid of your etching gear.

interesting.

Is there some easy trick to know how much HCl to add to regenerate your solution, and how to get the copper junk out after doing so?

Hmm, I've never heard of that before. Maybe I should give that a try.

Now, where would I buy this off the shelf in small quantities. :)

Jamie

Not completely. The copper junk in solution slows it down.

Etching only works if the stuff can stay oxidized. If you don't use it much, and leave the container open between uses, it will oxidize fairly well from atmospheric oxygen. Otherwise, adding an oxidizer such as bleach (sodium hypochlorite), sodium chlorate or hydrogen peroxide, slowly and with stirring and ventilation (mind the release of chlorine gas!), will oxidize it back.

Oxidizers will also enhance the etch rate. This is true even of pure copper chloride (which is the main byproduct of ferric chloride etching), which etches very slowly, in and of itself.

To remove the excess copper, you have to completely reduce the solution. The best way to do this is soaking scrap iron in the solution, which precipitates copper metal and reduces any remaining ferric (adding more iron to the solution). The resulting ferrous chloride solution must be oxidized first.

Tim

A pool supply shop will have HCL on hand, by the Gallon.

Chees

I was told, " The solution to pollution is not dilution" But as I recall the radio shack etchant bottle said dump it down the toilet. MikeK

Does that include old paint / paint cans?

Vermont had a truck that came around to the dumps every quarter or so, for the weekend. They'd take any household chemical, including paints. If you didn't want to wait for the "Rover", you could take the stuff down to the main office anytime during the weekday. I don't know what we do here. Haven't had anything like that to get rid of, yet.

Paints can be left to dry and then thrown in the trash. Adding some kitty litter will speed up the drying. Paint stores also sell a chemical that can be added to paint to speed up the solidification.

Add plaster, and you get a block that can go in the trash.

HCl can be bought as brick acid from many hardware stores.

NT

Over here: most drug stores and pharmacies sell HCl in 10% strength. When ferric chloride gets saturated a yellow sludge forms at the bottom of the tank. Add HCl until that disappears.

=A0 =A0 =A0 =A0 =A0 MikeK

Yep. Still says that today.

-- Cheers, James Arthur

AKA Muriatic Acid.

_Electronic Prototype Construction_ written by Dr. Barry Ornitz' co-worker at Eastman Chemical, Stephen Kasten , says to add it to mortar mix and send the lump to the landfill.

Mark Zenier snipped-for-privacy@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)

Which gives you twice the solution of copper contaminated hydrochloric acid. As I recall, you can plate the copper out by tossing a pad of steel wool into the copper loaded solution and the copper will plate out onto the steel wool. Neither steel nor copper is a hazmat; copper loaded spent etchant is.

Jim

Jim

So what is the procedure?

Do I reduce it with iron. Add HCI Then add bleach to oxidize

OR

If I reduce it with iron Do I skip the HCI Then add bleach to oxidize.

I have had three or four bottles of used Radio Shack Ferric Chloride on the shelf for at least 5 years. Can I make it work again? MikeK

PS. Don't try to warm a glass container full of Ferric Chloride on your wife's SS burner covers. The glass cracked and FC leaked through the crack and etched a long line into the burner cover. Luckily I noticed the problem before making a huge mess out of the stove.

Like many things, its hazmat status likely depends on the quantity.

Not really. You always lose some liquid due to evaporation. In my experience you don't need a lot of HCl to reactivate FeCl.