Airbrushing

[Kittyhawk]

I have a top feed airbrush which I am still learning to use and starting to get acceptable results from.
Essentially all I am spraying is varnish onto wood and the thing that really puzzles me is viscosity. I read everywhere to thin the coating to the consistency of skim milk and I can't visualize that. How do you differentiate between skin milk viscosity versus straight thinners versus varnish right out of the can which is a pretty thin product in the first place. My Mk.1 eyeball doesnt have the finesse for that. There must be some method ie counting drips off a toothpick or some such that would reliably give the correct product sprayability?

 

[mwinfrance]

try 10% thinners to varnish and test..if it's too viscous , advance in 10% steps..until it sprays ok..
test on a smooth bit of wood, not the final object.
mix in a small bottle.. not in the airbrush.