Industrial chemicals cause crazing on polycarbonate safety lenses
More and more customers are returning polycarbonate safety lenses exhibiting signs of “crazing” in the belief that these damaged lenses are defective. In many cases, the damage has been caused by the use of certain chemicals coming in contact with the polycarbonate lenses. Some scratch-resistant coatings help protect polycarbonate lenses, but because the edges are exposed, certain chemicals can attack the uncoated edge causing crazing and cracking of the lens coating. Please take time to inform your patients and employees to always clean their safety eyeglasses with mild soap and water instead of cleaning products and solvents. Here is a list of common industrial chemicals that can attack uncoated polycarbonate (Gentex®).
Hydrocarbons - Benzene, Toluene, Xylene
Halogenated Hydrocarbons - Methylene Chloride, Chloroform, Carbon, Tetrachloride, Triclean, Trichlor, Perchlor
Ketones - Acetone, Methyl Ethyl Ketone
Esters - Ethyl Acetate, Methyl Ethyl Methacrylate
Amines - Butylamine (Butylamine will attack coated polycarbonate also)
Commercial Materials - Industrial materials that can attack uncoated polycarbonate include gasoline and paint thinner.
For optimum, long-term clarity, the following cleaning procedures are recommended:
- Rinse with warm water or warm soapy water
- Rinse with clean, clear water
- Dry with a soft clean cloth
For long term optical lens life it is best to never clean the lens when dry. Your polycarbonate lens spectacles should always be placed in an appropriate protective case when not in use. Never place the front of the lens face down on any surface. With proper care your polycarbonate lenses will give you months of clear, safe vision.
How hot is the interior of your vehicle?
The interior of a car parked in the sun with the windows closed can get awfully hot. Exactly how hot? Take a look at the temperature chart above, with an ambient temperature of 105° F. Polycarbonate lenses are adversely affected by temperatures over 200 degrees Fahrenheit. The heat may cause fractures to appear in the lens. Never leave you glasses on the dash of your vehicle even if they are in a case!
