hi Terry,

Ammonium persulphate is very safe etchant. only problem is its cost. it costs her for me $5 /500gms. FC is $1.5 /500gms and Hydrogen Peroxide $1.5 /Litre HCL commercial grade $0.50 /Litre. But the cheap solution is corossive in nature. Hydrogen peroxide is an strong Oxidizer so Paper, Cotton etc may caught fire when in contact with the HP. Also on skin it cause the tissue dehydration casing white spots with burning feeling which dissapears with time. HCL also emits toxic fumes so a well ventilated space should be chosen when using this solution.


abhishek