The MythBusters The MythBusters

MythBusters Episode 217: Household Disasters

Premier Date: July 17, 2014

Certain types of sunscreen can make a human body susceptible to catching fire.


Adam began by spraying/squirting various types of sunscreen into a lighter flame to see if they would ignite. The cream formulations failed to do so, but the spray-on products did ignite due to their highly flammable propellants (butane and propane). For their next test, they set up a mannequin next to a barbecue grill and sprayed it with sunscreen once the grill was hot. One spray caused an arm to briefly catch fire.

Replacing the mannequin with a pig carcass, they investigated the possibility that the sunscreen could ignite even well after it had been sprayed on, due to the presence of flammable solvents. With the grill lid closed, they sprayed the carcass, waited a certain length of time, then opened the lid to expose it to the flames. Delays of 3 minutes and 1 minute gave no results, but a delay of 5 seconds did cause the carcass to catch fire. They judged the myth plausible, and Jamie commented that spray-on sunscreen could ignite in the short time before the solvents evaporated.

A piano dropped onto a house will smash cleanly through both the roof and the floor.


The Build Team found a one-story house slated for demolition, marked several target points on the roof between joists, and used a construction crane to hoist and drop various pianos from a height of 50 feet (15 m) above the roof. An upright piano weighing 700 pounds (320 kg) damaged the roof but bounced off without penetrating. A baby grand piano weighing 1,400 pounds (640 kg) pierced its legs through the roof but was unable to fully break through. Calling the myth busted, the team loaded another upright piano with enough sand to reach a total weight of 2,600 pounds (1,200 kg), much more than a full-size grand piano, then dropped it from 75 feet (23 m) above the roof. This time, the piano did smash a hole in the roof and landed on the floor.

A vacuum cleaner can explode if it is used to clean up black powder.


At the bomb range, the Build Team set up a carpeted floor and set up 7 vacuums of different types to suck up 1 pound (450 g) of black powder. None of them exploded after 60 seconds, prompting the team to declare the myth busted; they then used the powder to blow up one of the vacuums.

If a faulty water heater explodes due to pressure buildup, it can put out a nearby fire.


Adam and Jamie disabled the safety features on a water heater and connected it to a high-wattage external power source and a pressurized scuba tank, so that they could trigger it to explode on command. A test run spread water in a 25-foot (7.6 m) radius when the heater blew. They then built a one-story house with typical flammable furnishings, and included the heater and an ignition system in a trash can. With the pressure inside the heater rising, they started the fire, which spread quickly. At 300 pounds per square inch (2,100 kPa), they set off the heater, causing an explosion that tore the house apart; most of the fire was extinguished, but they did find some areas that were still burning. As a result, they classified the myth as busted.

A dog bowl can focus the sun’s rays at a small enough point to start a fire due to it being very hot.


The Build Team sets up a table on a wooden deck outside on a sunny day, made to look like a picnic, and put out highly flammable objects to improve their chances. This includes dried flowers, decaying wood, and paper. They set two types of dog bowls, metal and glass, in various sizes to focus the sun’s rays. Due to high humidity and wind, they use a theatrical light to warm up the set, replicating ideal conditions of the summer. The temperature of the set was 105 °F (41 °C), with 12% humidity. After two minutes, the glass bowls started a fire on the set, confirming the myth under ideal conditions.

(This segment was not shown in the U.S. broadcast.)

Putting on sunscreen near a candle can burn you.


Adam tests out if a candle can ignite sunscreen when applying it. He sprays it on a mannequin next to a lit candle, resulting in only brief flames that do not start the mannequin on fire. Adam then sprayed sunscreen directly through the fire, igniting the mannequin. Because this action was unrealistic, the myth was busted.

(This segment was cut from the broadcast but shown online.)