Step 3: Etch the Board (Instant Gratification!)
Open the bottle of ferric chloride and put the sponge over the opening, and tip the bottle to let about a tablespoon or so of solution saturate into the sponge.
Now with the circuit board in the palm of one hand, simply wipe the solution-saturated sponge over the surface of the board over and over. Don't scrub, just keep wiping it all over. In just a few seconds of wiping, you will see the copper start to disappear!
You will find that unlike the submersion etching method, the copper in the center of the board etches away first, so you might want to try to focus on the edges as you wipe.
In less than a minute of continuous gentle wiping, your board will be fully etched before your eyes!
Drop the etched circuit board into the bowl of water to stop the etching action.
If you are etching multiple boards, you can rinse out the sponge, squeeze out most of the water, then re-apply ferric chloride solution if desired, but I have found that I can etch two 2" x 3" boards with one application.