Hello
I just bought a spray unit from SPI called an lpg. It works, but we are still having a sort of love hate relationship. I need about 35,000 board feet so the trouble is worth it, at 1/2 price plus the gun. I've run over 90 gal through it and it hasn't killed me yet or the other way around.
Would I do it again....... I had my shop sprayed a few years ago and it took the guy 4+/- hrs and it was done, and looked like a professional job. Mine looks like my welding, which is to say about like a chicken walked over it and did his business. I don't think the looks affect the thermal performance, it sure does tighten the place up.
The other poster is right keeping the goop, hoses and unit warm is a problem, especially off grid in Alaska. I built a foam hot box for the goop and unit. I'm headed to buy a few more sets this week, so I'm either too cheap for my own good or just plain stupid, who knows. Make sure you have the correct respirator and protective gear.
I can tell you from personal experience, DON'T GET IT IN YOUR HAIR, I forgot to put on the hood.
Don't let it be said that I endorsed or condemn this method of getting foam on the walls, or in my case the roof from the bottom, I think it all depends on your pain threshold and endurance.
Have fun
Wade