What You Need to Know Before Using a Halloween Fog Machine

There’s nothing like a thick covering of fog rolling across the ground to create a spooky atmosphere, especially around Halloween. And the go-to choice for that effect is a fog machine. To learn more about these tools, I called on a seasoned pro.

James Willis, the author of more than a dozen books on weird and paranormal topics, has decades of experience using fog machines at various events. He has organized charity fundraisers in cemeteries and jaw-dropping haunted houses, along with investigating some of the most haunted spots in America. Willis explained how fog machines work and offered a few DIY insider tips.

How Do Fog Machines Work?

While there are multiple designs, the most common involves heat. These machines, or foggers, heat a mixture of water and glycol (aka fog juice) until it produces a warm, humid vapor. It pumps the vapor through a tube into the cooler atmospheric air, creating fog.

Other Types of Fog Machines

Heated fog machines are popular with DIYers due to their ease of use and low price. But alternate types are available. The simplest units cost less than $50, while massive machines that billow smoke across stages can cost thousands.

Dry ice fog machine

This type drops dry ice in warm water to produce low-temperature fog that hangs close to the floor and dissipates slowly. Affordable and easy to use, the downsides include safety concerns. Although non-toxic, dry ice displaces oxygen. You’ll also need lots of storage to keep a suitable amount of dry ice on hand.

Chiller fog machine

Sometimes called “heavy fog” or “ground fog machines,” chillers mimic the effects of dry ice. They use a thicker water/glycol blend and run hot fog through a refrigerator. Chillers are more expensive than a typical heated fogger, and beyond most DIY budgets.

Haze machine

Hazers use compressed air to force water or water/glycol droplets into a fine mist, creating a more subtle effect than traditional foggers. They run colder, but cost more and make more noise than traditional machines. Haze machines allow lights and lasers to stand out across a stadium. They’re marketed to professional touring companies or DJs.

Spooky DIY Tip: Build Your Own Chiller Thriller

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Heated fog machines are inexpensive, but come with a major drawback: heated fog rises from the ground and dissipates quickly. The solution? Cool the fog! “Cold fog will last longer,” Willis says, “so what you’re trying to do is keep it as cold as possible for as long as possible.”

A dedicated ground fog machine with integrated chiller can cost more than $1,000. Willis’s simple and affordable solution: PVC pipe and Styrofoam coolers.

Willis cuts holes in the coolers sized to the pipe diameter, slides one end of the PVC pipe onto the fog machine’s outlet, then runs the pipe through the ice-filled cooler. The result? Perfectly chilled, eerie fog that clings to the floor.

You can run the pipe through multiple coolers to maintain the temperature on long runs, and even decorate the cooler to look like a tombstone or other spooky decor.

Fog Machine Setup

When laying out your fogger, always place pipe where it won’t create a tripping hazard. And, of course, give some thought to how much space you want the fog to fill.

“When I wanted an entire cemetery to be filled with fog, I’d get a long, flexible pipe, like a drainage pipe,” Willis says. “Then I’d poke holes in the pipe every few feet.” This essentially created a big soaker hose, allowing the fog to leak out in select areas.

Spooky DIY Tip: Scented Fogs

Some fog lovers use fog juice infused with a specific scent. Commercial scents range from “cotton candy” to “charred corpse.” It’s a fun idea, but the cost can add up.

Instead, Willis recommends cheap essential oils. “We did one haunting that looked like an ocean scene,” he says, “and we used aroma therapy oil named sea breeze.” He says it was surprisingly effective, enhancing the audience’s experience.

Fog Machine Rental vs. Purchase

Two things determine whether you should rent or purchase your fog machine:

• Size of the event;
• Duration and number of event(s).

If you’re adding a little fog during trick or treating, purchase a small unit. For around $50 for the fogger and fog juice, it’s hard to beat that.

If you’re hoping to fog up an entire outdoor event, you’re going to need a bigger machine, with a bigger purchase price (roughly $350 to $500). For many people, a rental for $75 to $100 per night makes more sense. But if you’re doing a larger event every night for a week or two, the rental fee can quickly add up. In that case, invest in a higher end unit.

Willis started off renting, But as his events began running longer, it became more cost-effective to purchase. “The downside to that,” says Willis, “is you have maintenance issues to deal with.”

Fog Machine Maintenance

Fog fluid, especially the thicker, low-lying kind, is sticky when it dries. Willis had to trash more than one machine after finding it hopelessly “gunked up.” (We’re pretty sure that’s a technical “Haunter” term!)

You can purchase commercial fog cleaner, but Willis recommends mixing your own, using diluted dish detergent or vinegar. Once you’ve cleared the fogger of oily buildup, drain out all the liquid and dry it completely before storing.