Need to Create a Realistic Fire Effect? Build a ‘Humid-A-Fire’

Special theatrical effects can be so much fun to work on, but they can break the budget if you aren’t thinking imaginatively. Among the most challenging are those that incorporate the element of fire. Trying to create a simple, inexpensive fire effect without the use of an actual fire requires innovative thinking.

While I was the technical director at Triad Stage in Greensboro, NC, we faced that challenge on a production of Other Desert Cities. Scenic designer John Coyne had designed an open-faced fireplace in his post-modern set, and he wanted a fire effect. The show called for the fire to be as realistic as possible. The audience was situated so close to the stage that a cheap fire effect wasn’t going to provide the production value that was expected.

Initially we discussed the possibility of using an actual gas fireplace and researched the hoops we would have to jump through with the local fire marshal. However, after talking with the theatre’s production manager, pricing the hardware and gas supply, and looking at the overall safety concerns of a gas log fireplace, we realized we needed to be more creative and find a cheaper solution to this challenge.

Our answer: the ‘Humid-A-Fire’

The ‘Humid-A-Fire’ is shown in action on the set for Deathtrap, presented in 2015 at Triad Stage in Greensboro, NC. VanderVeen Photographers

Prop master Eric Hart, master electrician Liz Stewart and I combined efforts to create an effect that would go past expectations for this production. We found our inspiration in a video that Eric had seen online, showing a humidifier being used to create not just the look of flames but also of smoke coming out of the flames. After watching the video, Eric, Liz and I tested a variety of materials, dimensions and lighting effects to achieve a realistic fire effect. The resulting fire effect in Other Desert Cities was so successful we used it again for another production, Deathtrap, a year later.

We have named our system the “Humid-A-Fire.” Here’s how you can recreate this same effect in a production, using the materials detailed above.

Start with the PVC
Locate a well-ventilated area where you can clean, prime and glue the PVC pieces. Take the 1½” PVC pipe and drill ¼” holes spaced ½” apart from each other. The length of the pipe you use will differ depending on the size of your fireplace and the scope of the fire effect you are creating. Our fireplace used 18″ long pieces, and this length worked well to concentrate the humidity.
Once you have drilled your holes, attach the PVC cap at one end. Drill a ¼” hole at the bottom of the PVC cap so that the moisture that collects can escape the PVC tube. Failure to do this will cause the tubing to fill with water and hinder the humidifiers’ ability to pump into the PVC pipe.

Connect the 1½” flexible hose to the other end of the PVC tube. Then connect the flexible hose to the PVC “T” connector. PVC attachments are recommended, but hose clamps will also work. Use additional lengths of 1½” PVC pipe to attach the “T” connector to the two 90-degree PVC elbows. These cuts determine the spacing between humidifiers. The humidifiers should be spaced as close as possible, so there is less distance for the steam to travel.

The last step of the PVC assembly is to attach PVC inserts that will fit snugly inside the tops of the humidifiers. These inserts may vary depending on the kind of humidifiers you purchase.

Prepare the humidifiers
For this project, I used two Safety 1st Cool Mist Ultrasonic 360 Degree Gentle Nursery Humidifiers, which I purchased from Target for about $40 each. When working with this effect, you will need to verify with your electrical department that you have power supply for two humidifiers, a small fan and the LED tape and dimmer.

Once your PVC inserts are secured snugly inside the top of the humidifiers, test to ensure there are no leaks that will allow steam to escape. Once everything is in working order, use flat black spray paint to paint the PVC and humidifiers so they disappear when the burnt logs are placed.

If possible, make access to the humidifiers easy so you don’t have to disassemble and reassemble this effect each time you need to refill the water reservoirs. For our production, the humidifiers ran a few days without having to be refilled. How often you need to refill will depend on your show’s run and the amount of time the effect is used. You also need to plan for the condensation that will come out of the PVC cap; it will be more than you imagine.

Add light and fan the flames
Next, assemble your burnt logs in the fireplace, leaving enough room for the PVC tube to breathe. Lay the PVC tube in the middle of the logs and attach the LED strip as close as possible to the ¼” drilled holes using zip ties. Connect the wireless dimmer to provide power and control.

Waterproof LEDs are recommended. If you can’t afford that, wrap non-waterproof LEDs with plastic wrap to protect the equipment and provide a longer lifespan.

Once you have the logs assembled, the PVC tube in place, the humidifiers blowing and the LEDs secured, add a small fan to make the steam flicker. It may take some time to find the perfect placement and the best fan speed. You are looking to just barely move the steam as it pours out of the PVC holes; too much airflow will cause the steam to dissipate. The right amount of circulation will give the look of flickering fire that you are trying to achieve.

Try to use a black fan, or use the can of spray paint to turn your fan black. Any fan should work as long as it has a low setting and has a cone or tunneling effect. The fan I used was the Vornado Flippi V6 Personal Air Circulator, which I purchased at Target for about $20.

Final details
To complete the fireplace, add a few more burnt logs and pieces around the perimeter to add to the believability of the fire. Don’t add too many or you will change the flow of the “flickering” effect. If you can conceal a small fixture, consider placing a birdie or small PAR above the logs to give an all-around “glow” on top of the logs.
Cost-effective, realistic-looking fire

When assembled correctly, this fireplace insert will create lifelike flames that will leave your audience wondering if real fire was used. For very little cost, you can have a safe and professional-looking fire effect that will complement any production.

Materials Needed

(1) 1½” PVC pipe $10
(1) 1½” PVC connectors $10
(1) 1½” flexible hose $10
(2) PVC inserts that go into the top of the humidifiers $6
(2) Nursery / baby humidifiers ($40 each) $80
(1) Strip of RGBA LED tape (preferably waterproof LED) $80
Powered by the RC4 wireless dimmer with the flicker effect engine $449
(1) Small fan with a low setting $20
(1) Can of flat black spray paint $4
Assorted collection of burnt fire logs. Can be painted if needed.
Just slightly burnt, still need the inside integrity of the logs to hold up.
$0

Total: $220 (plus $499 if you need to purchase the wireless dimmer)

Steps to create the Humid-A-Fire effect

1. Assemble the PVC and add two humidifiers.

1. Assemble the PVC and add two humidifiers.

2. Place the waterproof LED tape and the wireless dimmer.

2. Place the waterproof LED tape and the wireless dimmer.

3. Position the burnt logs to obscure the fire rig.

3. Position the burnt logs to obscure the fire rig.

4. Test and adjust placement of logs, lights and humidifier tubes.

4. Test and adjust placement of logs, lights and humidifier tubes.

The completed fire effect is shown on the set at Triad Stage.

The completed fire effect is shown on the set at Triad Stage


This article originally appeared in Southern Theatre, The Magazine of the Southeastern Theatre Conference, Volume LXI Number 4, Fall 2020



Written by Chris Simpson
Chris Simpson is the technical director at Flat Rock Playhouse, the State Theater of North Carolina. He helped create this effect while serving as the technical director for Triad Stage in Greensboro, NC.

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