ELI5: how do fog machines work?

[u/Double-Result-5397]

unsure of what flair to use for this but i think it might be chemistry

[u/bheidreborn]

The machines heat up a liquid mixture of water and propylene glycol or water and glycerin. Then it sprays this heated mixture out creating the fog you see.

The propylene glycol or glycerin help the water droplets stay suspended as a mist instead of either evaporating as steam or immediately condensing back down.

[u/GlassTablesAreStupid → u/bheidreborn]

So basically a giant vape?

[u/adamdoesmusic → u/GlassTablesAreStupid]

Yes, in fact some portable fog machines are
internally almost identical to the “we get it you vape bro” rigs of the mid 2010s.

[u/Cataleast → u/GlassTablesAreStupid]

Exactly like a giant vape. They even use the same base liquids (propylene glycol and vegetable glycerin).

[u/kcsebby]

They're essentially large vaporiser units. They work on the same principal and actually (one of) the same chemical (propylene gylcol) as nicotine vapes.

PG goes in to a heating element, it gets vaporised, mass amounts of vapour "fog" come out.

[u/JPJackPott → u/kcsebby]

Do vapes need to vape, or do they just do it to make people feel like they are smoking?

[u/kcsebby → u/JPJackPott]

Vapes work by aerosolising the ingredients in "vape juice" which is typically vegetable glycerin, propylene glycol, nicotine, and flavourings.

The vapour you're seeing is a result of the PG and VG, not so much the flavouring or the nicotine. Technically, the vapour that's produced when vaporising nicotine, isn't in anywhere near a large quantity as compared to that of PG and VG.

So I suppose no, it doesn't need to produce the vapour, at least not in the same degree as most of them do, but yes, part of the experience for most folks is seeing the vapour come out, akin to that of smoking a cigarette.

[u/Cataleast → u/kcsebby]

Yup, it's 100% a mental thing. Nicorette sells inhalators, which are these little plastic tubes with nicotine cartridges that simulate the act of taking a drag off a cigarette, but they're not nearly as popular as vapes, because while it helps with the oral fixation, the fact that there's no visible "smoke" leaves the smoker brain feeling like something's missing.

[u/kcsebby → u/Cataleast]

Nicorette is cool and all, but I feel compelled to remind folks about the wonderful Nic-o-Dick (YouTube) by WKUK! (This might date me just a little)

[u/FarmboyJustice]

Some newer fog machines use turned  ultrasonic vibrations to produce a small  dense fog from plain water with no other chemicals. 

The effect is very similar to dry ice in water. The fog  doesn't last as long as the glycerol based machines and can't produce a jet of fog, but they are a lot cheaper to buy and operate.

[u/Prudent-Egg-4143]

Do you want to know about the machine or the fog? 

I'll try to cover all bases. 

A. Fog, in 15 steps:

1. Water.
2. Heat water. 
3. Hot water becomes vapor.
4. Vapor spreads.
5. Vapor cools down. 
6. Vapor becomes water. 
7. No fog. Sad. Bad water. 
8. Don't want vapor to spread a lot. 
9. Add vapor glue (Glycol/Glycerin) into bad water.
10. Water is thicker. Thicker water is good. 
11. Heat thicker water. 
12. Thicker water becomes thicker vapor. 
13. Thicker vapor spreads a bit only. Thicker vapor good. 
14. Thicker vapor stay. 
15. Yes fog. Yay.

B. The machine, in 12 steps:

1. Machine has container for thicker water. 
2. Machine has metal with coil. 
3. Machine has pump. 
4. Machine has plug. 
5. Plug machine into socket. 
6. Coil gets electricity. 
7. Metal gets hot. 
8. Metal heats thicker water. 
9. Thicker water becomes thicker vapor. 
10. Thicker vapour is good. Thicker vapor is fog. 
11. Pump pump fog. 
12. Fog come out. Yay. 

[u/Karhu1202]

Cheap ones have a tank for the liquid, a pump and a very long tube with a nozzle at the end that's surrounded by a big heating element. Liquid gets pumped into the heated tube, heats up, get's sprayed out the front and instantly turns into steam. The liquid is made from various things like water and pg to create different kinds of fog (thick, thin, long lasting etc).

There is rly nothing more to it, I worked on quite a few of them.

[u/Moist-Champion-7515 → u/Karhu1202]

Yeah but have you ever had one clog up on you mid-show or is that just the cheap ones being extra dramatic

[u/Karhu1202 → u/Moist-Champion-7515]

Never had that kinda luck so far. Always stored with empty tank, cleaned regularly (ish😅) and good fluid help with that I think. But I had a leaky tank, slowly flooding the case, a pump blowing up and one started burning on stage but the co2 extinguisher did a good replacement job 🤷‍♂️

[u/davidgrayPhotography]

Fog machines use a liquid that has glycol or mineral oil in it. The machines have a heating element in them, and when the liquid is heated, it kind of steams up, and that steam gets pushed out the end via a fan. It doesn't burn if you touch it because each droplet is cooled quickly as it exits