NWRA President's Column: The Crystal Ball

 In Colorado, where I have a repair and replacement business, one out of every three vehicles has a stone break, 17 percent of vehicles have an edge crack and approximately one out of ten stone-breaks cracks out into a floater crack.

As you may or may not know glass is more robust when it is cold because the glass molecules are contracted. When it is hot the molecules expand and it fractures easier. The same stone impact in the winter that does nothing would cause a break in the summer.

In the later part of December and the beginning of January this year in Colorado hit below zero degrees Fahrenheit overnight with daytime temperatures in the teens and 20s. I anxiously waited for the phone to start ringing off the hook because if that test were true than approximately 40,000 of the 150,000 vehicles in the county where I live would have cracked windshields during this cold spell and among the 14 auto glass shops in my county we would all be inundated with business. But it did not happen; the windfall did not arrive.

So I decided to brave the cold and go out and do another parking lot study, and here is what I found.

January 3 and January 4 the overnight temperature was -6 to -8 below 0 degrees Fahrenheit. In the morning of January third while it was still less than 14 degrees Fahrenheit I went to the Sam’s Club parking lot, but I had forgotten gloves and after 25 vehicles the pen froze. So on January 4, I went to the Wal-Mart parking lot and surveyed the remaining 75 vehicles (had gloves and a pencil this time). Out of 100 vehicles there were 45 chips, five of which had cracked out; ten edge cracks and; two miscellaneous breaks.