An Ikea glass cup placed on the bedside table of a man surnamed Wu spontaneously exploded early yesterday morning, sending sharp shards of glass in Mr. Wu’s hair. Luckily, he was not injured. 

Mr. Wu said the spontaneous explosion happened around midnight, which is when he was awakened by a loud bang. He said he would probably have been injured had his face been turned toward the glass. "Fortunately, I had the back of my head facing the glass cup," he explained.

It is thought that the cup may have exploded due to thermal shock; when an object’s temperature changes over time, it can cause parts of the object to expand by different amounts. However, according to Mr. Wu, he only filled the glass cup with room temperature water.

Mr. Wu said he bought four wide-mouth glasses of this kind for 4.9 yuan each from Ikea in Xihongmen, Beijing in February of this year. There were no safety instructions or warnings about spontaneous explosion on the label, and the glasses did not come with any packaging.

According to Ikea's customer service department, the glasses meet the company’s safety criteria. An employee explained, “Spontaneous glass explosion is a phenomenon that causes tempered glass to randomly break for no apparent reason. However, the chances of such an event are no greater than five in 1,000."

Ikea agreed to give Mr. Wu vouchers of equal value to the four glasses as compensation.