Blue asphaltum press resist

I have been printing resists with a print gocco/etch press system
using the rio grande blue asphaltum etch press resist that they
suggest. It is not the can of asphaltum that comes in the rio etch
press kit but the separate stuff they sell for the etch press. I am
having problems getting an even coating on my fine silver through
the screen and once I start etching with nitric it just floats off
the surface. I have tried slightly sanding the surface for the
resist to stick to but with no luck. Any info on printing with
different asphaltums and the print gocco or etching with nitric and
those same asphaltums would be very helpful. Thanks, Lilly