"I appreciate the tip on the gloss varnish. I didn't know you would have to thin it down to avoid the issue you had."
You shouldn't have to...depends on the varnish and your airbrush needle/nozzle size. I would normally use Vallejo Model Air but ran out a while ago so have been using Model Color thinned with a couple of drops of Vallejo thinner to ease the flow. The one I had a problem with was Vallejo polyurethane varnish which is quite viscous and, for me, needs thinning. I didn't thin it enough and airbrushed an uneven layer without me realising it. Gone back to using thinned Model Color until I can restock on model air.