Structural engineers have found that a freak phenomenon caused a glass roof to collapse at a Peterhead supermarket.
Nobody was injured when two large pieces of toughened glass fell from the roof of Morrisons into the entranceway of the store in September.
After a thorough investigation, a Morrisons spokesperson told the Buchanie it was caused by ‘sulphide inclusion’.
The spokesperson said: “An investigation was undertaken at the store by our expert contractors and all other glass panels were checked to ensure they were safe.
“Nothing untoward was found and the missing panel replaced.
“The inclusions occur as part of the manufacturing process and while manufacturers take every possible precaution to prevent it happening, they cannot be easily detected in the tiny number of instances when they do occur.
“We believe this was the issue in this case.”
The panels at the Queen Street store are made from toughened glass designed to shatter into ‘cubes’ to prevent injury.
Sulphide inclusions happen during the manufacturing process.
When glass is heated in the tempering process, any imperfections in the material are also heated.
The tempered glass is cooled incredibly quickly to finish it off, but sulphide inclusions cool much more slowly.
Eventually this can cause weaknesses in the glass which can - in a small number of cases - spontaneously collapse.
The phenomenon has been dubbed ‘glass cancer.’
In October 2012 two shoppers were injured in a similar incident when a panel from the entrance canopy shattered on top of them.
Both were treated for minor cuts.