Help, please: How is this accomplished, Polish specific engraved areas only

[LVVP]

I bought from KING CANADA, works very well

 

[Marrinan]

I have never tried with my micro blaster but they have liquid frisket as well. Used with paint like water color. You can also use thinned rubber cement. You paint over what you don't want blasted. Tombstone cutters use a much heaver duty stuff than standard frisket vinyl for deeper blasting. Fred