PU Gun


Everlasting foam dispenser

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.

-- Gaute Amundsen 12/10/09