On 3/5/22 4:23 pm, Morris Odell wrote:
Thanks to everyone who replied!
I do regenerate the solution by bubbling air through it from an aquarium pump but when I'm etching a board the solution gets darker faster than it can regenerate so I give it a little dose of H2O2 which brightens it up instantly. The dark color is due to the Cu(1) reaction product. Once it goes dark I leave the bubbling going overnight and it's as good as new in the morning.? Maybe my solution is too dilute but If I use a lot of it it's hard to see how the etch is progressing.
I'm in Australia where "safety" restrictions on chemical sales are inconsistent to put it mildly. You can buy big containers of concentrated HCl from pool shops but at hardware outlets it's kept under lock and key - go figure. You can get all sorts of inflammable solvents, poisonous pesticides and other chemicals from them with no problems. However the laboratory supply stores that were a fun part of my youth have all disappeared.
Anyway I might pass on the 35% H2O2 just because it's quite a nasty substance it it encounters something that will decompose it. The potential silver chloride problem is something I didn't know about either and I wouldn't relish having to clean it up. I guess the small bottles of 6% will have to do for my hobby purposes.
If it's a bit viscous, dilution with 1:1 water will speed things up.
HCl already has water in it, so that helps too.
Because of the success of air-ation, i've still got a 20L bottle of FeCl i got 20 yrs ago (i'm in australia).
