by model murdering » Thu Sep 26, 2019 6:13 pm
What we're looken for in the top coat is technically known as a "uniform liquid film". Easier said than done, of course. Most amateur painters have had enough bad experiences to be a little gun shy (no pun intended). My sense of it is that negative outcomes force inexperienced painters into altering the recommended technique.
Take a moment and watch a factory robotic paint job video. Then watch a trained humanoid painter, and note the similarities. The secret to spray painting is temperature, pressure, viscosity, distance, and time. Basically, you'll see crisp consistently controlled over-lapping strokes at a minimum distance, at the optimum temperature; with the liquid paint's viscosity and delivery pressure precisely controlled.
Obviously bomb painting ties the hands with respect to pressure and viscosity. The contents are limited to a fixed nozzle size, so it's important to maximize the efficiency the orifice, so you get the best atomization possible. This is why heating your bomb can is critical.
The natural tendency is for folks to creep the shooting distance out. Pulling back extends the distance, and thus the time a droplet has to unliquify enroute to the surface. The actuality is that you want to be close enough that the atomized liquid paint remains liquid until it can hit the surface of the work piece, flow out, and lay down.
Folks who catch me painting always say something along the lines of, "Wow, you're really close." and "Boy you're really moving."
The truth is I'm at the minimum shooting distance and moving at the required feet per second, to lay an evenly over lapped liquid film, with no runs.
More later.