Tempered Glass Furniture Shattering

Tempered glass is still safer than standard glass.

Temperature changes in your home can cause glass furniture to explode (WEST PALM BEACH, Fla. ) - With a hammer, a Window Doctor employee struck a piece of tempered glass. Blow after blow, the glass held up. Due to that strength, furniture makers prefer using it. However, some consumers have found a downside.

"I'm surprised. I'm shocked," explained Patty Velez. Velez was watching morning television when a noise upstairs startled her. "It was loud enough it scared the dogs," Velez explained. Velez ran upstairs, and couldn't believe the mess in her room. "This whole glass was shattered like it is here," Velez said as she showed us her damaged glass cabinet. "And it was bowing three or four inches out and I could tell it was just ready to go." Within seconds, "It finished exploding and all the glass fell to the floor. It continued crackling and popping almost like popcorn on the floor."

What happened here, could happen to you. "It's common in the industry," explained Gary Orman of Innovative Window Concepts . Orman said all homeowners should beware. "You never know when or if it's going to happen," Orman said. Orman said tempered glass spontaneously shatters from normal expansion and contraction from temperature changes that  might occur in your home from air conditioning and sunshine.

"Tempered glass is tempered in a heat oven and brought up to a certain degree temperature and cooled quickly to make the glass stronger. It puts the internal pieces into compression and the external pieces into tension, and gives strength to the glass," Orman said. "There are particles in there that do not melt and those particles will change as the heat changes." "It's 4 out of 1,000 pieces that do it," Orman said.

Four out of a thousand may not sound like a lot, but there are dozens of complaints with the Consumer Product Safety Commission for patio furniture, shower doors, desks, and glass cabinets. "Would you buy another piece of furniture like that?" Strathman asked Velez. "No definitely not," Velez said.

Despite the examples, furniture makers say tempered glass is actually safer. So we set up a demonstration with the Window Doctor. We used two pieces of glass that look the same, but there's a huge difference when hit. We compared annealed or standard glass with tempered glass. After just one hit, the standard glass shatters into large sharp pieces that can easily cut you. With the tempered glass, after one hit in the same spot the glass is still in tact. Even after six hits, not a chip or a crack.

"With tempered glass the edge is what takes the tension," said Orman.

So we put the hammer to the test on the edge of the tempered glass. It took 8 hits before the glass shattered into a million pieces. The size and texture of the tempered shards are much smaller and duller compared with the annealed glass. "It might be safer but it can still cut you," Velez said.

"Now that you know this happened to other people what do you want the manufacturers to do?" Strathman asked Velez. "I think they need to tell people there is a possibility this could happen with this type of glass," Velez said. Velez's furniture was built by IKEA. Their website warns customers to handle the glass with care especially the edges which in "exceptional cases can cause the glass to break suddenly." Something Velez wishes she knew before she was left cleaning up a mess.

After our calls to IKEA, they replaced the glass in the broken cabinet and another piece of furniture to make sure this doesn't happen again. It's an issue that can impact any tempered glass furniture -- no matter the manufacturer.

Also See:  

Spontaneous Shattering - Tempered Glass - A Guide For Window Cleaners

Glass Shower Doors Can Shatter Without Warning

Annealed Glass As A Health Hazard

Windows Shattering in Dubai - NiS Problems?

Glass & Imperfections - Report Those Unsafe Windows

Annealed Glass As A Health Hazard

Annealed glass breaks in to shards.

Older Glass Windows Are Potentially Deadly: Lean against or touch certain glass windows and doors and you can actually be putting yourself in danger. CBS 2′s Dave Savini shows how the danger lies with how the glass is made. “This is a deadly weapon,” says glass safety expert Mark Meshulam as he shows a sharp, jagged broken piece of glass from a window. “This is just crazy.”

The type of glass he is talking about is called annealed glass. It is found in windows in older homes, schools and storefronts exempt from more current rules requiring safer, tempered glass windows. Tempered glass breaks into small pieces, while annealed breaks into large, jagged ones that can cause greater injury. There have even been deaths.

Fifty-two-year-old Michael Racky lost his life after falling through a glass window. His adult children, Meghan and Sean Racky, say their dad leaned against an annealed plate glass window in Oak Lawn, and it shattered, nearly amputating his leg. “It hurts a lot,” Meghan Racky says. “I have to wake up every day realizing, I’ll never see him again.” They say a BB-gun hole compromised the window three years earlier. “It’s actually a very big problem that many people aren’t even aware of,” Sean Racky says.

Tape was used to hold it together, says the Racky’s attorney Tom Paris. “Packing tape is not an answer for compromised glass,” he says. CBS 2 found that tape is being used on other annealed glass windows in Chicago, including at a Laundromat and a daycare. Meshulam says they are dangerous. The 2 Investigators found 6,069 city citations were issued for window code violations between 2010 and 2013. “Somebody, sometime, is going to go into that glass,” Meshulam warns outside one building.

Maria Elena Gonzalez was standing outside of a South Side apartment building in 2006 when she was struck by a falling window. “The pain was unbelievable,” says Gonzalez, who had never thought about the danger a window could pose. The 2 Investigators went back to the building where Gonzalez was hit by the window and found five more broken windows.

Annealed glass windows and doors are being blamed for deaths around the country, including a Pennsylvania art professor who fell through a glass door at a restaurant and bled to death. The solution, Meshulam says, is simple, and he demonstrated. He struck a tempered glass window with a special weight bag; initially, the glass failed to even break. It did break on the next test, but broke into tiny pieces instead of the jagged shards of annealed glass.

Building codes can vary by community, when it comes to the type of glass required in homes and businesses. Safety glass is pretty much mandatory in doors, but not all windows are required to have it. Houses and other buildings built before 1977 were not even required to have safety glass. If you are not sure what type of glass you have, look at the corners. Safer tempered glass typically has the manufacturer’s logo etched into it. Attempts to reach the business and building owners were unsuccessful.

Annealing is a process of slowly cooling glass to relieve internal stresses after it was formed. The process may be carried out in a temperature-controlled kiln known as a lehr. Glass which has not been annealed is liable to crack or shatter when subjected to a relatively small temperature change or mechanical shock. Annealing glass is critical to its durability. If glass is not annealed, it will retain many of the thermal stresses caused by quenching and significantly decrease the overall strength of the glass. The glass is heated until the temperature reaches a stress relief point, that is, the annealing temperature (also called annealing point) at a viscosity, η, of 10¹³ Poise = 10¹² Pa·s, at which the glass is still too hard to deform, but is soft enough for the stresses to relax. The piece is then allowed to heat-soak until its temperature is even throughout. The time necessary for this step varies depending on the type of glass and its maximum thickness. The glass is then slowly cooled at a predetermined rate until its temperature is below the strain point (η = 10^14.5 Poise). Following this, the temperature can safely be dropped to room temperature at a rate limited by the heat capacity, thickness, thermal conductivity, and thermal expansion coefficient of the glass. After the annealing process the material can be cut to size, drilled or polished.

Tempered Glass links here.