That is called "backflash".Quote:
Originally Posted by mikebarger
The correct way is to aim the CO2 in front of and below the base of the fire, and sweeping up, slowly - cutting off the oxygen supply progressively - from the base up.
The way it was explained was that if you "blanket" the fire, it will search for oxygen by spreading rapidly in every direction under the blanketing cloud. Not technically accurate - but close enough in practice.