Etching with Ammonium persulphate

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Joined: 31/07/2019
Location: Australia
Posts: 328
Posted: 10:59am 31 Dec 2021      

A cm depth of solution works ok for me, definitely 70 deg + is needed. Biggest hassle I had was sometimes buying an old pack that had gone off, if the pack is over two years old or so just chuck it out and get a new one. Once it is heated the solution decays so I usually use a fresh mix if I can.
The copper forms a black oxide as a halfway step as it etches, if you start getting persistent "shadows" the solution is getting iffy. The solution goes blue with the copper as  it etches as well - don't use the blue solution with a stainless steel utensil or you will copperplate it as a grotty stain. An old plastic tray works ok.
Edited 2021-12-31 21:00 by zeitfest