Dipping the fret

So the point of those pics is to show basically what i do and to present -vaguely for the moment- the devices I have been building.
The red thing is the etch tank done out of a morning chocolate box, which is pierced and plugged to an aquarium air pump.
I take the fret between 2 wooden bits and secure the whole in a strong clamp (If i were to dip the clamp in the ferous oxyde, the metal parts would be attacked by the acid)