Tag Archives: thermal expansion

Shattering Glass Cookware

By Kim Smiley

Did you know that glass cookware comes with directions?  Many consumers aren’t aware of that fact or know that there is a risk of their trusty cookware shattering if the directions aren’t followed.

This issue can be analyzed by building a Cause Map, a visual root cause analysis.  To begin the Cause Mapping process, an Outline is filled in with the basic background information.  The impact to the goals is also listed in the Outline.  In this example, the safety goal is impacted because there is a possibility of injury if glass cookware shatters.  The schedule goal is also impacted because of the possibility of messes and ruined meals.  This issue has also generated some negative publicity so it is also an impact to the consumer service goal.  The next step is to ask “why” questions to determine what things contributed to the issue.  These causes are then added to the Cause Map to visually show the cause-and-effect relationships between them.

In this example, the glass cookware explodes because it is subjected to temperature swings and it isn’t able to withstand the change in temperature.   Modern glass cookware isn’t as resilient to temperature changes because it is made of a different material.  Starting in the 1980s, glass cookware started to be manufactured using soda lime silicate glass.  Originally, glass cookware was made with borosilicate glass, which is significantly more resilient to temperature changes.  The change occurred because soda lime silicate is cheaper, more resilient to impacts and better for the environment.

Many consumers aren’t aware that modern glass cookware is different from what they may have grown up using.  As a result, consumers may not be following the new directions and this may cause the cookware to explode.  Many consumers may not even be aware that glass cookware comes with directions.  The directions can be found on the manufactures’ websites if the original packaging was tossed.

A recent article in the American Ceramic Society Bulletin that looked into the issue found that modern glassware is far less resilient to temperature changes and concluded that the margin of safety is borderline.  Consumer Reports also looked into the issue in 2009 with a dramatic video showing shattering cookware.  Consumer Reports warned people to carefully read safety warnings.  Manufacturers of the products stand by their products and are fighting to have the American Ceramic article retracted.  Visit the Pyrex and Anchor Hocking’s website for more information.

If you would like to report an incident of shattering cookware, please contact the Consumer Product Safety Commission at 800-638-2772 or info@cpsc.gov.