Dry Ice

Contrary to the common perception the fog produced with a dry ice machine is simply water vapour.The dry ice is simply a very cold medium to cool the water vapour[steam] and cause it to lay on the floor.It is very inconsistent, as it depends on the humidity of the venue as well as the temperature.It can only be used in short bursts as the water cools down in the machine and it ceases to function.In short avoid it like the plague unless you have time to experiment with it and never ever use it over an orchestra as the water vapour will stuff up the instruments and the musos will kill you.