I am currently still making test plates, but the results look promising. To keep the process as non-toxic as possible I used Amsterdam Acrylic markers, Lascaux Hard Ground and lithography pencil for my first test plates.
First step test-plate was made using only acrylic markers. I drew with the markers and used them also as the stop-out varnish. They were in 3 different sizes and had different paint solutions - transparent, semi-transparent and fully covering. Clearly the markers started to erode but the conclusion is that the best protection was achieved by the semi-transparent one.
For the second plate I made a drawing with the lithography pencil (soft). After the initial 15 minutes of etching I used Lascaux Hard Ground as a stop-out.
For the third plate I drew with the same markers as before but used Lascaux Hard Ground as the stop-out.
After the plates had been etched I used the non-toxic (but potentially irritating- wear gloves) soda-ash solution and a toothbrush to strip the paint from the plates.
I also tried the Pebeo acrylic paint remover witch worked faster but I am not entirely sure about the safety as the ingredients are not listed on the bottle. It smells, is regarded irritating but can be washed of with tap water. I have yet to test the power of the Orange oil cleaner witch should work as well.