Two years removed from its release, Netflix’s Squid Game has returned to the spotlight, albeit much lighter, following the recent release of Squid Game: The Challenge. Though deaths are removed from the newly released reality series, it includes all the events featured in the Korean drama, including the infamous Glass Stepping Stones challenge.
For those unaware, the Glass Stepping Stones in the original show featured a glass bridge perched high above the ground. Contestants were tasked with jumping across the bridge comprising 17 glass tiles separated by a few feet of air.
The glass was strategically designed to be either annealed or tempered. Contestants who landed on the annealed glass broke through and fell to their deaths. Contestants who landed on the tempered glass were spared. The twist was that contestants who went first were most at risk, while those who went last could pick their way around the broken glass tiles.
To avoid people pairing on a single tempered glass tile, the challenge’s organizers from the original show designed the glass to be just weak enough so that it shattered. It’s a design strategy that is thankfully not used in the real world. According to Julia Schimmelpenningh, architectural industry technical manager for the Advanced Material Interlayers business of Eastman Chemical Company, glass floors are typically designed with a minimum of three layers of glass, two layers being able to support the load with the third to be redundant in case of breakage. The recent tragedy in Indonesia showcased how poorly constructed glass bridges can lead to death.
Unfortunately, the original show’s contestants were not afforded the same rigorous design considerations used for most glass bridges. However, one contestant, who said he was a glassmaker, claimed he could discern the difference between annealed and tempered glass by faint marks visible when the glass was lit from the side. This allowed participants to determine which glass to jump on up to a point. Officials from multidisciplinary engineering consulting firm ARCCA Inc. said that while it’s possible to tell annealed and tempered glass apart, the process is not as cut and dry as depicted in the original show.
“Annealed glass is normally not birefringent–it does not polarize light,” said officials in an article titled The Glass Bridge from Squid Game. “But the residual stress in tempered glass can cause it to become birefringent, and this is especially noticeable when there are slight variations in the residual stress. Sometimes, if you wear polarized sunglasses, you can see that variation in tempered glass car windows. So perhaps someone could tell the difference between tempered and annealed glass by how it polarizes light. But that would require some kind of polarization filter. The clever glassmaker contestant in Squid Game did not have any such filter–so he probably could not have used light polarization to tell the difference.”
The participants in the new reality series don’t have to worry about differentiating between annealed and tempered glass. The glass tiles on the show’s bridge were made of Perspex, a type of clear acrylic, not glass. Contestants also didn’t fall more than 100 feet to their deaths. They had stunt doubles who ran onto the bridge and fell 16 feet onto a six-foot-tall airbag positioned underneath.