Great British Chefs demonstrates how to make foam with a gas canister at home.
1. Pour the seived liquid into the cannister and screw the top on
2. Select your preferred nozzle and screw that on
3. Screw in your gas cannister (you should hear the gas rush in)
4. Chill or keep warm depending upon your recipe instruction
5. Shake can vigorously before use and press down to make the foam