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A craft hack for “fractal wood burning” is killing American DIYers.
An electrical engineer tells us why it’s so dangerous, and we also suggest alternatives.
In an alarming video published last week, food scientist and YouTube personality Ann Reardon discusses a dangerous craft hack called “fractal wood burning,” which creates striking designs in a slab of wood that look a bit like lightning strikes. To do it, users gut a microwave, then use its transformer to connect directly to a wet piece of wood, forming a circuit with the wall plug, she explains.
According to the American Association of Woodturners, at least 33 people have died attempting fractal wood burning projects since 2016. As recently as April, two people died from electrocution using this method, yet folks continue to share this “hack” on YouTube and TikTok. Some have even devoted entire stores on Etsy or Amazon to selling their results—for honestly far too little money, considering the ridiculous danger involved in the DIY method.
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If this all sounds bonkers, you’re right. We spoke to an electrical engineer to set the record straight about the dangers involved in this method, as well as to find a couple of (safe) alternatives if you’re looking to create a similar effect without, you know, dying.
What Is Fractal Wood Burning?
Reardon describes fractal wood burning in detail in the video above (skip ahead to 7:20). First, people take a discarded microwave and remove the transformer from inside it. Then, they use a split plug to connect to the live ends of the transformer, and use jumper cables to connect the other side of the transformer to a wet piece of wood. This forms a circuit and delivers voltage from the wall, through the transformer, and into the wood. Power travels across the wet surface, which is conductive; then the dry wood beneath is burned as the electrical energy raises the temperature.
What you end up with is essentially a homemade Lichtenberg machine, an apparatus used to embellish wood. To understand the dangers here, we spoke to Philip Krein, a research professor at the Grainger Center for Electric Machinery and Electromechanics at the University of Illinois’s Department of Electrical and Computer Engineering.
First, we wanted to know exactly what makes a transformer ... a transformer. A transformer is a device that links two electrical circuits. “The circuit potential—the voltage—is proportional to the number of turns of wire linked to that circuit,” Krein explains. By varying the number of turns of wire on both sides, we can connect devices that would otherwise be incompatible. We can also, for example, take electrical current coming in on major urban power lines and “transform” it down for household use so all the homes in the world aren’t immediately fried. (Imagine if the only flow rate of water available to you was what you see coming out of an open fire hydrant!)
“The transformer in a microwave oven steps up the voltage to deliver a few thousand volts to the magnetron tube that generates the actual microwaves,” Krein says. “Most devices that connect to the grid also have transformers, including very small devices that drop the voltage to 5 volts or so for cell phone charging, devices that step up the voltage for fluorescent tubes, and power supply interfaces in almost everything.”
Why Are Homemade Wood-Burning Machines Dangerous?
The microwave transformer is surprisingly powerful, too. “A transformer that can deliver several thousand volts at power levels up to 1,000 watts is extremely dangerous, which is why the power supply in a microwave oven is fully enclosed in metal and not accessible to a user,” Krein says. “Some say that ‘current kills’ in an electrical setting, and any electrician will agree that equipment with a voltage much higher than 240 volts and power levels able to deliver a fraction of an amp is extremely dangerous and even deadly. A 2,000-volt transformer can force plenty of current even through the driest skin—or the smallest flaw in a pair of gloves.”
This is something Reardon also discusses in the video, because some people have waved their hands and said that it’s safe if you use heat-proof gloves. But there are so many variables, including simple and obvious things like if you happened to trip and lean your elbow or other body part against your setup. Or a child or pet could run into the room and surprise you. (Squirrels pretty regularly blow up entire power grid transformers.)
“At the voltage and power levels we are talking about, standards for ‘arc flash protection’ kick in, with very extensive requirements for training, protective clothing and gear, and procedures,” Krein says. The arc is a special situation wherein the electrical current is finding an unideal path to try to still close the circuit, which creates a dangerous, violent, loose “arc” of electricity. “It is hard to imagine that any U.S. workplace would be willing to expose workers in the manner shown in these craft kits. It is stunning to see this stuff for sale on Amazon,” Krein says.
⚠️ Warning: Do not purchase fractal wood-burning kits for sale online—even if their manufacturers promise that they are safe alternatives.
Safe Alternatives for Wood-Burning Projects
So, what can you do if you like the look of these fractal wood burning projects, but don’t want to die for them or support the cottage industry around them?
First, there’s a cool object you can buy, or possibly locate at a shared maker space or even public library near you. It’s called a PyroPrinter, and it may not even be the only “burning printer” of this type that’s available. This device uses a hot tip to burn-print a design onto a piece of wood, based on image files that you upload to the linked computer or Android device. It’s basically like an automated version of the wood-burning “pen” or wand you would use yourself. To find a design you’d like to upload, try looking for images like lightning strikes or close-ups of the vein patterns on leaves—other naturally-occurring patterns that have fractal-like qualities. You could also use a photo of an existing fractal-burned piece to create a new pattern.
The second option is more scrappy, but it could still really turn out beautifully. You can find a lot of wood-burning kits online, but these markers chemically burn the wood. All you have to do is draw on a design in pencil and trace over it with the markers, which have multiple tips for different effects. Then you use a heat gun to set the material and burn in the design. And again, you can start with lightning or leaf veins, or an image of fractal burning and transfer it manually onto your piece of wood. It’s a bit labor intensive, but you’re in virtually no danger.
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