Ammonium persulphate

Only if it's cornered or feels threatened.

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Not aluminium, but I think some aluminium alloys have copper in them. My electric sunbeam frypan I used to keep the etchant warm got quite pitted, presumably due to the etchant eating out the copper, or whatever else was there. Seen it with others too.

So don't use Mum's frypan to heat you aluminium persulphate solution. Get an old one.

Regards Barry

It certainly attacks copper when heated up.

Regards,

Charles L

I keep mine (ammonium persulphate) in a small aquarium. around 12 X 8X 8 Inches. Unfortunately the fish died. It certainly attacks them I also found a fish tank heater does the job well for heating. As well as all this, a small fish tank aerator helps etch the copper of nicely if you let the bubble run up the inverted board Almost sorry the fish died, but this all works well. My wife's sunbeam is safe, for now.