hello guys i just try to make ferric chloride for pcb etching. i put some iron in a bottle and add muriatic acid its dissolved all the iron and turn into green color. then i put air pump pipe into it and after couple of hours its turned into brown color. i put some copper pcb in it just to try it. its doesnt etch the copper its turning copper in a little grey color but no etching. i put some iron in it and its starts reating with the iron but not with copper at all. i tryied copper wire also it dint react with it what is the problem . i heated up the ferric chloride too its didnt do anything either why is that