Sterling Silver resist for etching

Does anyone know of a spray paint that can be used as an etching
resist on Sterling silver? I am using one that is an enamel based
paint. When I etch into it, it flakes. Any other ideas for a good
resist would be great. I am trying to stay away from Asphaltum which
is messy. Any help would be great!

Thanks!
Beth

Lacomit is a traditional resist for most tempertures of acids.

Nick Royall