glad lotus
First of all, nice job! Second, you made that way harder than it needed to be.
Here’s how I would have done that.
Completely cover the backside of the metal with duct tape (any color).
On your card stock final pattern, use a “craft knife” to cut away anything you do not want etched, creating a stencil. (Use your laser if you have one.)
Position your stencil on your metal. Use a sharpie and fill everything in. Remove the stencil.
(The hot glue dots was a good shout.)
Place your metal in the acid solution until you get the desired effect.
Remove the metal from the acid solution until it stops bubbling.
Remove from the neutralizing solution and remove the duct tape.
Wash with hot soapy water to remove the neutralizing solution residue and any tape residue.
With a cotton ball or small rag soaked in rubbing alcohol, wipe over the front side of the piece to remove the sharpie and clean up the piece.
Buff with 0000 steel wool to remove any remaining discoloration (unless you like the look).
Apply liver of sulphur as shown in the video if desired.
An alternative treatment would be to brush the low areas with solder flux and use a torch and go over the piece and watch the magic happen. Let it cool completely because the metal gets hot.
You can gently buff the raised area with a fine emery cloth if desired.
Enjoy your finished piece.
This also works on copper.
jolly moss