Keeping Low-Lying Fog Low Lying

[Spader]

We are (trying) to use low-lying fog in my current show. The dry-ice machines that we tried both didn’t work (we figured that the pump that pumps fluid through the machine was broken –on both of them) so we hooked up a regular fog machine to a modified cooler that we fill with dry ice. Low lying fog pours out of the cooler and fills part of the stage beautifully, but only for about five seconds. The second it meets air conditioning or dancers, it is picked up, mixed with the surrounding, much warmer air, and becomes regular fog, filling the theatre and obscuring just about everything. Does anybody know of any ways to get low-lying fog to hang out low to the ground and under control? How is this achieved in larger theatres?

[Footer]

The Aquafogger

Pretty much the defacto standard dry ice fogger. You might want to experiment with quick dissipating fluid in your fogger, it might help. Otherwise, dry ice is one of the only inexpensive ways to get low lying fog.

[thatactorguy]

We have a couple of Pea Soupers that work pretty well; the pressure build up is what forces the dry ice fog out...

Dry ice can wreak havoc on latex painted floors, so be be careful- it can get slippery...

[Spader]

Thanks for the input, but unfortunately we don't have the budget (or the space) for the Aquafogger...but I know that the manager at our theatre is looking into better dry ice foggers to combat this. I will definitely suggest the pea souper to him.

Are there any conditional, quick suggestions you guys might have, or is it just that our equipment won't give up what we want?

[sk8rsdad]

You could try using a dry ice chiller to cool the chemical fog more. "Quick dissipate" fog fluid will cut down on the amount of fog that appears to be in the air.

LeMaitre makes a fog fluid (Molecular Fog) that is designed to bond with CO2 but you need one of their "DryIcer" units to mix it.

[mrtrudeau23]

if you have space for fans, i have used them in a few shows to push the fog where i want it to go. it works quite well, and i'm sure you could use some small ones mounted overhead to push the fog down. it's something you may have to play with a little bit, but worth a try.

[Brownlight]

Hey
On low fog the secret is CO2,and getting the right mix, with the right kind of fog juice. The air flow of your HVA system will affect it also. It all depend on how far you need the fog to flow and how big of an area. I may be able to help you. let me know

[Spader]

Our air conditioning wreaks havoc....I'll try to get a few fans and see what they do when I'm at a pickup tomorrow.

[Dalamar]

Good mroning everyone,

just a few quick notes here:

• The "secret" to low fog is... temperature. the Low fog generators we make will chill the fog to a lowly ~ -70 C (-120 C, with L-N2), thus creating a constant low and dense carpeting white fog. If you cannot chill the fog enough, it will rise and mingle with your atmospheric effect. There is now way to do it with conventional means and dry ice (which is in fact CO2). They simply do not keep fog cold enough for long enough. As much as I which we could forgo the use of L-CO2 (or L-N2), it still is the best way to get the result.
• Many manufactuers will provide solutions with L-CO2
• Low pressure gets better result than high pressure, especially on larger stages.
• The reason fog rises and does not dissipate in time is because the fog fluid used has too high a density of DEG (Diethylene Glycol) or TEG (Triethylene Glycol) in it. Try using a fluid labeled as a "low lying fog fluid".
• No matter how cold, any draft of air, including that from an actor or dancer passing through the fog, will make it rise. Velocity, chill factor, type of fluid and barometric pressure will dictate the ensuing dissipation speed and RoR (Rate of Rise).