pyrotechnic-assisted cannon. But it's cheap, it makes a terrible mess and it goes off with a satisfying bang, so it's the next-best thing.

We're posting this in honor of the 2010 World Series champion San Francisco Giants, who will be receiving their own ticker tape parade on Wednesday. So, if you're stuck at your desk while the Giants are riding around in downtown SF getting showered with adulation and tiny bits of paper, you can have your own little private party while you watch the web video stream.

These simple mechanisms are noisy, messy and a little bit dangerous. So, please use your best judgement when constructing them and setting them off.

This article is part of a wiki anyone can edit. If you have advice to add about confetti grenade technique, log in and contribute.

What you'll need

Film canisters. The clear kind work much better than the black kind. Each one will be filled with confetti and blown open by air pressure. They will get squished or bent after a few explosions, so you'll need a few of them.

A can of compressed air. The kind with cold liquid propellant used to clean electronics and computer keyboards, available at any office supply store. You'll get better results from a brand new can than from an old one. Get a can with a straw on the nozzle.

Confetti. Empty out the reservoir of a three-hole punch, or cut up some shredded paper with a pair of scissors. If you're a Mr. Moneybags, buy it in bulk at the party store.

How to proceed

What we're going to do is pressurize the inside of the film canister by putting a small amount of liquid propellant into the canister, then closing the lid on top of it.

When the liquid comes out the can, it's very cold. Once inside the film canister, it begins to warm up, and the liquid evaporates and turns into a gas. With the lid on, the gas is trapped inside the film canister. The pressure builds as more of the liquid turns into gas. Eventually, the pressure will blow the top off the canister.

Extract the juice

This is exactly what the warning label on the canned air tells you not to do, so be careful. Don't do this anywhere near your face.

Flip the compressed air can upside down and stick the straw inside an empty film canister. Gently squeeze the trigger on the compressed air can, and you'll see some clear liquid dribble out of the straw. Let about half a centimeter or so dribble into the bottom of the film canister.

The liquid is very cold and the fumes are noxious. Don't squeeze the trigger too hard, or else the blast of propelled air will cause the liquid to splash onto your skin, where it can give you frostbite.

Fill it up

Dump in your confetti. Make sure none of it gets caught under the lip of the lid -- the film canister must be able to close completely without any obstructions. Go ahead and pack it in there, just don't compress it too much.

Be sure to work quickly. The liquid is evaporating, and you need it to pressurize the container when you slap the lid on. Five or six seconds should be all you need.

Close it and wait

Press the lid down firmly. Your confetti bomb is now armed. Flip the whole thing upside down and put it into position with the lid facing downwards. Put the armed grenade on a table or a few feet behind an unsuspecting co-worker.

In around 20-60 seconds, the confetti bomb will explode. The canister will bounce off the ceiling, leaving a trail of confetti behind it. Stand clear when it goes off, it really flies.

What the pros use

Check out this pneumatic confetti cannon made from an old fire extinguisher, a tube, a hose and some various plumbing-grade fittings.

This page was last modified 23:33, 2 November 2010 by howto_admin.

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