Supposedly, apparently, pros use metal pistol attachments for nozzle-less expansion foam canisters. Does anyone know why?
AFAICT, the pistols are a bit costly. The pistols themselves can get clogged and add a maintenance burden. You need to then buy a can of special cleaning solution (is it acetone?), to spray through the pistol after every use.
I have always used the foam for DiYers: a canister with a nozzle and long plastic straw. The straws are trivial to work with: you twist a screw into the end of the straw when done to seal it off. The stuff in the straw still dries out but it’s easily cleared by plunging it. A coat hanger can push it all out in one piece.
Twice those things have fucked me. I buy a huge can of the stuff and use it for one small squirt somewhere. Then the stuff cures inside the can near the outlet, thus sealing it off. There is no recourse because label even tells you that you’re going to get fucked. The label says “one time use”. Indeed, they expect you to blow the whole load in a single giant ejaculation. WTF? Now I have cans of barely used expansion foam with lots of liquid trapped inside the can. I don’t recall if I tried the spraying it upside down trick to clear the nozzle.
So I have to wonder, is the pro stuff any different? Wouldn’t the pro canister outlet self-seal just the same? A hardware store near me is going out of business and I have a chance to buy a pistol at ½ price. Not sure it’s worth it.
The metal pro guns flow a lot more and have way better control over the flow. Awesome to use on big jobs. They do require cleaning. It will still cure in the nozzle.
With single use cans sometimes the spraying them upside down thing works but if you're trying to get another use do that, take the straw off, and stick a piece of wire into the little tip on the can. The foam expands as it cures. You just need a little hole for it to get through and the pressure can push some blockage out.