So Bryan and I tried the airbrush and the plaster of paris particle size was too large to go through the air brush even after considerable thinning. I finally tried the solution with a cheap detail gun and it worked great. Bryan applied one coat and then used the heat gun to dry the piece rapidly. Then he applied a second coat and repeated the heat application with the heat gun. The resulting surface was quite even. We set up the Rhino file and finalized our settings using the afore mentioned settings. It worked like a charm! Check it out.
I believe this is working due to the chromium content of the stainless steel. Stainless has a passivation layer that is thin and completely transparent; Chromium oxide. When combined with calcium sulfate (plaster) along with the heat from the laser and potential water from the surrounding air, you end up with calcium oxide and chromium sulfate. Chromium sulfate creates the mark and the calcium oxide washes off. Again this is my basic premise and understanding of what’s occurring here.
If you slow the laser down, it will create a darker etch/mark. Higher wattage lasers should be able to reduce the power a bit from my 100% power setting on the Epilog Zing 40 watt.