How to Identify the Manufacturing Date from Car Glass?
3 Answers
The method to identify the manufacturing date from car glass is as follows: There will be a trademark in the corner of the car glass, consisting of several dots and a number. The number represents the production year of the car glass. If the dots are on the left, it indicates the first half of the year, while dots on the right represent the second half of the year. The production of car glass involves heating the glass in a furnace to near its softening temperature, then rapidly transferring it to air grids with different cooling intensities for uneven cooling. This creates different stress levels between the main viewing area and the peripheral areas of the glass. Generally, such glass is zone-tempered glass. The peripheral areas are located in the strong air flow positions of the grids, requiring full tempering, resulting in good fragmentation and high tempering strength. The main viewing area is in the weak cooling position of the grid, leading to larger fragments and lower tempering strength.
Look for the glass markings in the corners, those dots and number combinations. Dots generally represent the last digit of the year, with their left or right position indicating the month. Dots before the number signify the year—for example, two small dots might mean 2012. Dots within the code segment indicate the month, such as dots followed by a number representing the month. I learned this when I first bought a used car, checking the windshield markings to determine if the glass was original. For instance, '..4' could mean manufactured in 2004 or 2014. Inconsistent dates suggest the glass was replaced, possibly indicating an accident history. Regular self-inspection can boost confidence when buying a car. Details like glass aging are also relevant, but this is a simple starting point.
At work, I often teach people to identify glass dates: glance at the code in the corner of the window, the number and position of dots determine the year and month. Dots on the left indicate the last digit of the year, dots on the right represent the month. For example, '•3' might mean March 2013. An incorrect date suggests the glass is not original, possibly due to collision repairs, which helps assess the vehicle's safety condition. The only tool needed is your eyes—no instruments required. Keep the language casual but easy to understand. Sharing this little trick can help car owners save on professional inspection fees.
