# Fog fluid myths



## Hippofeet (Nov 26, 2012)

I just helped design and test some fog fluid. This included fluid of every flavor from the major players. Here is what I found.

All fog fluid is some percentage of propylene glycol/glycerin/triethylene glycol to distilled and purified water.

A fogger should have cleaning fluid run through it at thge end of every season. No. I have more returns when I either don't test a new fogger at all, or I run cleaner through it before shipping. The best result comes when I run a good quality fog fluid through it for testing, and leave the intake tube full of that fluid, so that there is no time that the pump runs dry. I have anecdotal evidence from customers that leaving the fluid in the tube until next season results in fewer pump failures. Hard for me to say, I only have a few test foggers that are seasons old, I tend to intentionally break them for testing, and constantly cycle in new pumps and exchangers.

Fog fluid separates after freezing. Yep. It does. I froze some. The layers are visible. Shaking helps, but I would still hesitate to use fluid that has frozen and thawed. If nothing else, the difference in what is going to pump (the semi-seperated distilled water and glycol) will result in a difference in the appearance of the fog.

Shelf life. I don't know. I have fluid from the same manufacturer that is over a year old, all 5 bottles have been open (but the lids screwed back on) for that time, and 1 bottle is clearly bad. I have strained a few of the bottles through a filter, and used the fluid to no ill result, but I would not recommend it. To me, its the cost of a new bottle of fluid, versus the cost of a new machine, or at least a repair. Add in shipping back and forth (depending on the company) and that fluid starts to look cheap. The bad bottle clogged the intake tube filter in minutes,and was easily identifiable as a thick slimey coating. Poured out on a table, and there were strings in it, but I still dont know what caused the difference in thickness. I'm leaning toward bacteria, but that's purely a guess. I just know that after 8 months open on a shelf, that bottle went south, and if I hadn't been right there, it would have killed the pump. The difference in fog output was easily noticed.

There is no magic formulation to make fog fluid that will be chilled. Any percentage of the above will perform as expected through a chiller, with a fast dissipating being better for indoor use, and the longer the hang time, the more the resulting fog will heat up to ambient air temperature, and form a haze in the air. It has more to do with rapid cooling than the content of the fluid. Honest.

Purity DOES matter. Impurities in the water, or in the glycol, will cause deposits in the heat exchanger, and kill the fogger. The more pure the water and glycol, the more expensive it is to make the fluid. Buying by the truckload can get you down into the sub 1 dollar area per pound of glycol, which if you run the percentages out far enough, means most of the price is in the distilled water, and in shipping that water.

Fog fluid is necessary to "cool and lubricate" the pump. Not true. I ran a 1500 watt fogger pretty much non stop for 2 weeks (see another thread where I killed the test fogger on tap water) on distilled water alone, the pump is in great shape, even after killing the heat exchanger with tap water over the course of 27 hours the first time around.

Ground Fog Fluid is formulated to interact with the humidity in the air, or the temperature and moisture of the ground. No way. There is just no way that is true. The temperature will have a bearing in that as the fog heats up, it will rise. The lower the air temp, the lower the temperature the chilled fog needs to be to keep it down on the ground. The percentage of glycols to distilled water has nothing to with it. I have done enough now to know that the same fluid in the same machine will act differently in July at 2 pm than it will in October at midnight. It's the air temperature, not the fluid.

A fog fluid has to be matched to the machine, and you have to use the manufacturers recommended fluid. Why? If the machine will not reach a temperature inside the heat exchanger that will cause the formation of undesirable elements, such as formaldehyde, then what could the reason possibly be? The pump will run on distilled water, or 100% glycol (although it will bog down the pump, possibly shortening its life span). The thermal switches on the heat exchanger have more to do with this than the fluid. I see this as an attempt by manufacturers to sell fluid more than anything else. Will they void your warranty if you say you used "brand X"? Maybe. If so, they are jerks, because there is just no difference in fluid to justify the action. But, how could they tell? If you return a fogger that has failed, are they going to send a sample wipe of the fluid to an independent testing lab? Heck no. So how do they determine what has been run through it?

You should never build a home-made fogger. Not true. Its just math, like anything else, and control. If you know the temperature that glycols break down into undesirable ethanols and formaldehydes, and you know how to use thermal switches and thermostats to control the temperature of the heat exchanger, and you can measure the temperature of the heat exchanger, then why would that be? How do engineers design foggers? There's no magic numbers involved. The machine either gets hot enough to boil the distilled water/glycol mixture, but not so hot that it burns it, or it doesn't.

So that's my take on fog fluid so far. I will post more as I learn. Conflicting opinions are more than welcome here. If I am wrong, I will own it. I just don't think that fog fluid deserves the mystique that seems to surround it.


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## Lunatic (Oct 3, 2006)

Good information Hippo, thanks for sharing!

I developed water based coatings for over 22 years and used tons of glycols. I agree with your observations and assumptions. 

Interesting that you saw a stratification of the fluid after freezing. Glycols have a very low freezing temperature and that's why they use it for auto antifreeze. I expect the phase separation of all the ingredients were created by each components different freeze thaw temperatures. We used propylene glycol in a line of craft paints to protect them from freeze/thaw viscosity instability during shipment and warehouse storage. But that was to protect the polymer in the paint which can effect the polymer structure if it hard freezes. 

In the past, I've had some Froggy's fluid for a few years stored in my cold garage with no problem. However, It probably never got as cold as what you tested. Without knowing for sure, because I've never evaluated it, I would expect that the fluid would mix back together if warmed up a bit. How low of a temperature did you freeze the fluid?


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## MR David Person (Sep 30, 2013)

I have had my fog machine since 2003 and never once used a fog cleaner and I have yet to replace anything on it so this info is interesting to me.


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## Zurgh (Dec 21, 2009)

So, will rubbing fog fluid all over your body allow one to float on the fog?:googly:


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## Hippofeet (Nov 26, 2012)

Zurgh,

For some reason, when all of us that work here were testing the glycerin, it got really warm when we rubbed it all over each others bodies. It gets alarmingly warm, really. But none of us floated. Maybe we just need thicker fog?


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## Hippofeet (Nov 26, 2012)

Lunatic,

Another company I do some tooling for uses glycols in skin care products, and it's considered an emulsifier. 

My freeze test wasn't even scientific enough to put a thermometer in with it, but it was in a regular freezer. Maybe I need to try a different range of percentages, or agitate the bottle longer. Could very well be that the bottle that went in the freezer just didn't get shook enough. I will try it again, and see if it turns out different. Also see if I can freeze regular glycerin. It shouldn't, but I need to see.


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## Hippofeet (Nov 26, 2012)

Mr David Person,

See? That's what I mean. Why would leaving it there hurt a fogger? Doesn't make sense to me. And whats in fogger cleaner? Vinegar? A mild acid solution? Distilled water and some **** and span? Its impossible to know, no fluid manufacturer lists ingredients. If you ask for an MSDS on fog fluid (because you breath it almost everyday for hours) you get a piece of paper that says "all ingredients are non toxic and food safe". From my research, that's true, but what is in it is proprietary, and they wont even disclose it on a legitimate MSDS request. And it doesn't really answer the basic question. What's in this stuff?


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## Copchick (Apr 10, 2012)

Very interesting information. Thanks!


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## [email protected] (Aug 25, 2012)

I like this discussion.... Based on your observations Hippo, I can see why manufacturers would recommend running a cleaning solution thru the fogger before long term storage. As you've seen, some fluids exhibit separation after freeze/thaw, and some experience microbial growth (or whatever the cloudy, stringy goo is). If you are unlucky enough to have one of those situations inside the fogger pump/lines, you could be in for a clog. The cleaner is probably designed to leave no residue and inhibit growth of any kind (my guess).

If I manufactured foggers, I would also recommend that customers only use "my" fog fluid. The reason I'd do that is (as you pointed out) purity matters. I wouldn't be able to guarantee the lifespan or performance of the fogger with Brand X fog juice. However, if Brand X is just as good or superior, there should be no performance issues. I completely agree.


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## MR David Person (Sep 30, 2013)

Hippofeet said:


> Mr David Person,
> 
> See? That's what I mean. Why would leaving it there hurt a fogger? Doesn't make sense to me. And whats in fogger cleaner? Vinegar? A mild acid solution? Distilled water and some **** and span? Its impossible to know, no fluid manufacturer lists ingredients. If you ask for an MSDS on fog fluid (because you breath it almost everyday for hours) you get a piece of paper that says "all ingredients are non toxic and food safe". From my research, that's true, but what is in it is proprietary, and they wont even disclose it on a legitimate MSDS request. And it doesn't really answer the basic question. What's in this stuff?


I often leave fog in my fog machines after each haunt and they all still work 
and never once did I use cleaner's of any sort so yeah. In my opinion fog juice can last forever as long as it is not left open in the air (like what happened to my 5 gallons of fog juice this year), and further more I have yet to make any repairs to my fog machines and there 10 years old and still kicking.


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## Lunatic (Oct 3, 2006)

Hippofeet said:


> Lunatic,
> Another company I do some tooling for uses glycols in skin care products, and it's considered an emulsifier.QUOTE]
> 
> Not to sound like a smart-ass but technically glycols are high boiling-point solvents. Sad to say, but glycols are used in most personal care products and their toxicity have been debated for years and yet we still use them...even in food products. Egad!
> ...


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