Was it this?
https://www.amazon.com/Speedball-3940-Professional-Relief-Supergraphic/dp/B06Y5W6MBY/ref=sr_1_10?crid=K7ORFVP7IX5&keywords=speedball%2Bsuper%2Bblack%2Bindia&qid=1704287407&sprefix=%2Caps%2C124&sr=8-10&th=1

There is another Speedball version which they sell to be brushed or used in pens, etc.
https://www.amazon.com/Speedball-2-Ounce-India-Super-Black/dp/B0007ZJ8TM/ref=sr_1_2?crid=K7ORFVP7IX5&keywords=speedball+super+black+india&qid=1704287407&sprefix=%2Caps%2C124&sr=8-2

Nothing I'm seeing says anything about shellac.

_________
BrentD, (Professor - just for Stan)
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