- A metal IKEA bowl can be used to start a fire, but the company isn't going to recall it.
- Mike Tuts, professor and chair of the Columbia University physics department, says the fire occurs because the bowl is parabolic in shape.
- This could happen in any metallic bowl, not just the one from IKEA.
It's pretty easy to start a fire in the Blanda Blank IKEA bowl, but the company isn't about to recall the product.
Last week, a Swedish man claimed that the serving bowl he purchased from the retail giant had caused his grapes to catch fire when he left them out in the sun on his balcony.
He went on to post a video on Facebook showing a piece of newspaper smoking when he held it in the sunlit bowl.
Despite the attention his video received last week, IKEA said that it would not be recalling the item or removing it from shelves.
"In risk assessment for the bowl Blanda, it has been established that many different parameters would have to converge for the content of the bowl to overheat and that the risk for this to happen is very low," the company told CNBC. "The round design of the bowl further contributes to a very low risk of spreading, in case of any overheated material in the bowl."
But, it turns out that it's pretty simple to start a fire in IKEA's bowl. I know, I did it.
I purchased the IKEA bowl, grabbed a brown paper bag and went in search of some sunlight.
To mimic the Swedish man's claims, I placed the bowl in direct sunlight and let it sit for about 20 minutes before tearing up a piece of the bag and holding it in the bowl.
It took several tries — and a burned finger — but after a few minutes, the paper began to smolder and smoke.
I tried this several times with different size pieces of paper and in different locations within the bowl. I found that the paper only ignited in one specific place in the bowl and that the longer and thinner the pieces were, the easier they were to burn.
The brown paper never ignited into a flame, but it clearly was burned by the sunlight.
You see, the bowl has a parabolic shape, which means that when the rays of the sun reflect within it, they meet at a single point. If you hold an object, like a piece of paper or a grapevine, at that point, the rays get concentrated enough to raise the temperature of the object and cause it to burn, Mike Tuts, professor and chair of the Columbia University physics department, told CNBC.
(Source: Mike Tuts, Columbia University)
In fact, it is the same method is used to light the Olympic torch before the ceremonial games.
The torch is placed in a parabolic mirror, which like the bowl, focuses the rays into a single point and ignites the fuel in the torch, creating the flame. The tradition dates to the original Olympic games in Greece.
The science explained by Tuts would occur in any metallic bowl, not just the one from IKEA.
"One small point is that you want the object you are setting on fire to be small, because if it were large then it would obscure the sun's rays and there wouldn't be any light to concentrate," Tuts said.
That explains why the thinner pieces of paper were easier to burn.
On a larger scale, this phenomenon occurred in London in 2013. A skyscraper dubbed "the Walkie Talkie" was built in such a way that it would act as a concave mirror.
The sunlight would hit off the building during certain points in the day and melted pieces of the parked cars below.
While the metal bowl isn't likely to do that kind of damage, it might be best to keep them out of the sunlight this summer.