Sounds to me like your bath is contaminated. Is it possible that some other metal has come in contact with the bath? I never let things sit in an etch, I either mount them in a holder or a basket and swirl them around during the process. After your ammonia and rinse do you dry the pieces? Spotting can occur if you do not. I would hold them in a water bath until the next step.
Howdy Bill, I did get good colors after the cleaning. I use plastic
forceps when ‘dipping’ and a pyrex bowl (on the side burner of my
grill), no other metal around. After rinsing off the ammonia the
pieces were laid out on a paper towel on a cookie sheet, they may
not have been completely dry. Next time I will xfer them to a
distilled water holding bath or rinse in distilled water and dry. Is
that what you’re suggesting? BTW-I marked my etching solution with
the expiration date when I mixed it up - April '02 - how quickly and
in what manner will it ‘go bad’? thanx Carl 1 Lucky Texan