Re: What is the best way to create fog\\smoke?
Bit of terminology difference here, what used to be called `smoke` machines are now more usually referred to as `foggers`. Because people, especially paid talent, have concerns about breathing in `smoke`.
Foggers, previously known as smoke machines, uses water based glycol fog, glycol is used in things like cakes to make them remain moist. They work by pumping the fluid through a heater block which turns it into basically lingering steam.Heavy use will eventually leave deposits on things as the liquid condenses, but the key term is Heavy use.Low cost machines abound.
Dry ice foggers are water boilers that when frozen CO2 is dropped in , sublimes back to gas and the cold CO2 makes the moisture content in the air turn to fog. These are the classic low lying fog effects. Dry Ice is quite hazardous to handle , it freeze burns, is expensive and the effect is very short lived.
Hazers are a third type of atmospheric effect,used to create a very light but long hanging haze , not as dense as fog but enough to pick up light and laser beams. They use mineral oil and `crack` it into tiny droplets either by ultrasound like the atomiser someone else mentioned, or by compressed air, these machines are expensive.
CO2 jets similar to fire extingushers do exist, but the effect is very short lived and the equipment is expensive.
Liquid Nitrogen is used in some theme parks to create `natural` fog, cost and complication puts it at the space launch end of atmospheric effects.
Anything you use to fog up an area should be safe to breathe, buying a commercial product and using the manufacturers reccomended consumables, should ensure your safety.
Fog in a can is OK for the very occasional user.
HTH
Adam
