Long ago (maybe 45 years) my old company evolved mostly into a spray foam roofing contractor from just an insulator. Because of the iso particles and small size screens, and yes, not doing a good job of sealing the iso drums. This was always a recipe for a pile of disaster. I kept shooting myself in the foot and no one would help to unload the gun.
If you are spraying with a #1 mixing chamber, use no smaller then #60 screen in the spray gun and machine. Use your logic to know the size of the A-B ports of mixing chamber and screen size openings.
Screen sizes examples. #80 is 80 openings per sq. Inch. #60 is 60 openings per sq. Inch. #30 is 30 openings per sq. Inch. The lower the number the larger the opening for particles to pass through. As you go up to a larger size let’s say for higher volume output (roofing) you may want to use only #30. Many times I sprayed without filters and it all worked out fine. Nothing that I have said will fix anything long term without making sure your materials are free from exposure.
