Perhaps no component of making fog or smoke is as misunderstood, or as underrated, as the fluids used in the process. Fog fluids used in these processes are made from a series of glycols mixed with water. Glycols are among the most commonly used chemicals in the world and are found in products from food to cosmetics. The choice of which glycols manufacturers use should be made very carefully.

Fog machines and fluids are designed as systems. Specific fluid formulas require specific temperature for optimum aerosolization during the “flashing” process. Manufacturers of fog equipment design their machines to be compatible with their fluids. If a machine is calibrated at too low a temperature for a given fluid, the result can be “wet” fog that can leave a residue. If the temperature is too high, the fluid can “burn” or decompose the fluid, thus changing its chemical composition. This “burning” can create harmful byproducts.

In a recent report, an agency of the US Federal Government, the National Institute of Occupational Safety and Health (NIOSH) recommended “using only fog fluids approved by the manufacturers of the machines”. (HETA 90-355-2449)

On a Side Note: i happen to notice that no one has mentioned if you make a second chamber with nothing but ice in it connected to the fogger with 2 holes so the fog runs through the second chamber it will cool the fog so the fog doesn’t just fly everywhere. honestly if you are going to have fog for halloween it is best when it sticks to the ground, because when you have the fog come directly out it is coming out at that hot temp and just rises up. it is way better to have a chiller box attached IMO.

How is it possible to get the fluid to evaporate at a temperature higher than it evaporates?

Or rather, water boils at 212F, so how do we get the water up to 220F?

The answer is: a fluid will not reach a temperature higher than its evaporation point(for the particular pressure it happens to be). The gas can get hotter but never the liquid.

So this would be fine and plenty safe.

“Excessive, repeated exposure to glycerine may cause increased fat levels in the blood.
Glycerine has not caused cancer in laboratory testing, nor did it cause birth defects or other fetal effects.”

From: http://www.dow.com/PublishedLiterature/dh_01ad/0901b803801ade92.pdf?filepath=productsafety/pdfs/noreg/233-00490.pdf&fromPage=GetDoc

Making of:
Do a two small holes in the cap of the jar. Little less than the diameter of the air pipe.
Cut the tubing in half to get 2 pipes.
Put one end of the first pipe inside the cap, down to the bottom of the jar.
Secure the end of the second pipe at 1/4 inch or less after passing the hole.
Attach the free end of the second pipe to the air pump.
Plug the air pump into the Christmas lights controller.
Assure the pipes with the hot glue.
Disassemble the hot glue to get the heating element.
Fit the free end of the first pipe to the glue bar intake of the heating element.
Maybe and depending of the construction of the heating element, will be necessary that another more heat resistant element be fitted between the tubing and the heating element.

Use:
Fill the jar with smoke liquid almost to the top and put the cap on.
Connect to the wall outlet the heating element.
Way a few minutes and connect the Christmas light controller too.

Enjoy the smoke.

Now I just need to find a good heating element. :)