Lori - you might try a different approach to this. If you first
apply your choice of blackening patina - liver of sulfer, silver
black or anything short of acrylic paint - to your pieces. Cover them
well in the letters, but neatness doesn’t count here.
Then use a vibratory tumbler with a coarse media to get the
sandblasted look or a medium to fine media for a satin look. Run the
pieces for 15 minutes and the excess black will be gone. Run them
longer and the tumbler will do all of your finishing job.
If you want a bright shiny finish, follow the abrasive run with
stainless steel in a rotary tumbler. The letters will stay black, but
the apparent contrast is less because everything is shiny.
Tumblers are a perfect answer to making a patina stand out on
texture without messing up the texture.
For more get the book - Tumble Finishing for Handmade
Jewelry - it has the detail you need to evaluate the process and make