Initial experiments with home etching. Mordants either CuSO4 or NaCl + CuSO4
The most interesting result so far was to get a really good line etch by using just a piece of felt soaked in CuSO4 and sandwiched between an old copper plate and the aluminium plate connected with a copper wire.
This process was first invented in 1840 and patented. But it fell out of favour and all the older toxic chemical etches - which involved asphaltum, lead and mercury etched in either sulphuric or nitric acids kept going.
The electrolytic process is clean and green by comparison. It took me about a month to get both line and aquatint tone under control. But it's on the way. Next stage is to apply sugar-lift and coffee-lift spit-bite and carborundum gradients.