A man has said how he heard a "loud boom" that he thought was something smashing into the roof of his house before he discovered that his shower door had "exploded". It left shards of glass across his bathroom.
Peter Sullivan, from Donaghadeed in County Down, Northern Ireland, told BelfastLive: "I'd never experienced anything like it. I heard a loud boom, like a large object had smashed onto the roof at the rear of the house.
"But when I ran upstairs to see if anything had come through the ceiling, I could hear was a cracking sound. I opened the bathroom door, one of the shower doors had exploded and the glass that was still in the frame was continuing to make the cracking noise for about an hour.
"It was a mess - there were tiny shards of glass all over the place. Because the screen door was still cracking, I was afraid the rest of it would go, so I got out of there and let it settle.
"That shower door is about 12 years old and has had plenty of use over the years, so maybe it was getting worn or damaged, I don't know, but my wife put the photo on Facebook and lots of people responded saying they had experienced something similar.
"People mentioned they'd seen pint glasses explode with no one near them, oven doors when the oven was not even warm, garden tables, a huge fish tank, one lady said her fridge shelf exploded, another said her bathroom shelf blow up and other people experienced similar with double glazed windows in their homes.
"It's a bit scary to think it could have happened when someone was actually in the shower. Given the distance the shards travelled and the noise of the bang, there must have been some force behind the moving glass. It could have caused serious injuries, but thankfully we were downstairs and out of harm's way."
How can tempered glass explode?
To make it durable, manufacturers of tempered glass subject this material to high amounts of pressure. If a practically invisible chip or crack on a sheet of tempered glass occurs, a sudden temperature change could cause it to shatter.
However there appears to be no single convincing theory to explain why shower doors spontaneously explode, although glass expert Mark Meshulam, says toughened glass has a huge amount of energy stored within it and all of that energy is trying to get out.
During the manufacturing of toughened glass microscopic pebbles, called nickel sulfide inclusions, can sometimes be trapped inside the glass and as the glass and pebbles expand and contract with the heat, the pebbles may weaken the glass causing it to explode.
Mark said: "Glass can also shatter due to poor installation, pre-existing damage and imperfections. Extreme temperature changes can also cause shower glass to shatter, however, the temperature shifts between day and night are not likely to cause this phenomenon."
