Quote:
Originally Posted by updraught
from the Glass Encyclopedia. "Sun-Turned" glass is glass that has changed colour because of exposure to strong radiation. ... When irradiated or exposed to sunlight for a long time, this glass turns yellow. The effect can be seen in the headlamps of very old cars.
http://www.glassencyclopedia.com/irradiatedglass.html |
So the American lenses used arsenic in the manufacturing process and the British used manganese? And both would have been clear when new?