PU Gun
If you ever had occasion to use expanding polyurethane foam to mount a window or the like, you may have thought like me “Great stuff, wonder what else I could use this for?” But standard polyurethane foam cans are only good for a short while. Once used, the valve and application tube glues itself shut within a few hours, regardless of how much product was left in the can. Keeping a can around for those odd jobs and bright ideas is just not worth the waste.
Enter foam guns. The point of foam guns is right up front, so to speak. The exit valve is right up at the very tip of the rigid application tube. When you mount a can to the gun, the whole inside of the gun is pressurized with product just like the can. There is nowhere inside where the foam can expand or harden.
That’s the theory, at least. In practice it still won't keep indefinitely. On first try mine hardened right trough in two weeks, and I had a nasty job cleaning it out mechanically. Subsequently, I have taken care to store it with the can upside down, and I tested it every few days for a while, and now it seems to keep fine for at least two weeks. Perhaps it just needed to self-seal.
I don't have a particular brand to recommend. I just got the cheapest all-metal model on eBay at the time, which I've seen since both branded and unbranded, and at wildly different prices. My experience seems to indicate, though, that staying away from the plastic models was a good idea, as I had to use considerable force to disassemble the gun for mechanical cleaning.
With these caveats, I'm still pretty happy about this discovery of mine. Only this week I used it to assemble a life-size doll my girlfriend made, and fix it to its plastic pipe skeleton. It really feels like I've got a whole new material in my kit.
Discovering what else it’s good for is going to be fun.
Available from Amazon
Also from eBay
Favorite (15)
Irving Washington
Another trick with can foam and possibly a foam gun... Ice maker line is the perfect size to fit can foam. Most of the time, the plastic straw that came with the can is fine, but there are plenty of times when it's impossible to hold the can upside down and get the foam where you want it. In those cases, I hack off a foot or two of ice maker line so I have a nice long flexible straw that I maneuver overhead, or deep into a recess while the can stays nicely upside down. Then when done (which is usually before the can is empty), leave the line on the can, the foam will harden inside the line and seal the can. Next use, just take the old line off, throw it away, and cut a new one.
Don
Any user comments about using Great Stuff Pro Gun Cleaner for cleanup?
Matt
I use the trick posted on Toolmonger about a year ago (http://toolmonger.com/2008/11/19/reader-tip-great-stuff-spray-foam/), sticking a pipe cleaner soaked with WD-40 in the straw for storage. This has worked great, even for several months at a time. Several commenters also mention that cleaning the straw and nozzle with acetone solves the problem as well.
Norm
My biggest problem is the cans seem to have a very finite shelf life, used or unused. I've picked up some a couple times when they were on sale just to have on hand and when I went to use them a year or so later they were dead.
Will
Irving, thanks for the ice maker line tip, that's handy to know. My company is a contractor for our state's Weatherization program, and we shoot a lot of foam. My opinion is that Todol foam guns are the way to go, and that EFI is the place to buy them. The $35 one is really a pretty hot deal and all you need if you're not doing blower door guided air sealing (if that's you, get the expensive one.) Great Stuff in cans is hopeless compared to anything with a check valve that actually responds to your will while you're using it. The blue plastic "industrial" Great Stuff gun is better, but not good enough when you can get the Italian one for $35. You want the thing to stop when you let go of the trigger, especially after the first time you get it on your hands or in your hair.
Zorlack
Expanding foam is a lifesaver ins so many situations, but any recommendations regarding expanding foam should come with some pretty serious warnings.
Expanding foam is chocked full of isocyanates which are extremely hazardous at any concentration. Furthermore there really is no approved respirator cartridge to use when dealing with these chemicals. Short of having a fume-hood, or a pressurized filtered breathing apparatus you shouldn't be using these chemicals on a regular basis.
One other note. After curing, most of these products continue to emit small levels of toxic fumes. You should factor that in when considering where to use expanding foam.
-z