I've been experimenting with etchants and have come up with a simple and fast one.
1 ounce Muriatic acid from the hardware store
1 ounce BAQUACIL Oxidizer from pool supply store (27% H2O2)
2 inch by 4 inch, 1 ounce solid copper. no traces. Etchant was at room temperature and I agitated the board with a foam paint brush.
Etch time 10 seconds!!!!!!!!!!!!!
give it a try.
BAQUACIL Oxidizer
A chlorine-free liquid oxidizer of 27% specially-stabilized hydrogen peroxide used to clarify pool water by oxidizing organic compounds (swimmer waste).
http://www.baquacil.com/Products/coreProducts.htmPS Do this outside wearing safety goggles! Lots of fumes.