Never tried acid etching myself. This might be worth noting: If your PCB is lying flat in the bottom of the etch container, the disloved copper will leave a film on your PCB. This effectively acts as a barrier between the PCB and etchant. The answer is to agitate the PCB or as mentioned, use something like a paint brush. Also mentioned is highter temperatures which usually speeds up chemical reactions - sometimes to a mad gallop. :-) Peter Shetland Islands. [Non-text portions of this message have been removed]
Message
Acid etch time
2012-07-10 by Peter