Blue Headlights?

[The Bedford Boys]

When lined up they look clear, but when driving out of the gate, they look blue to me.

The lenses are two pieces of glass with a blue film sandwiched between them. So natural light can reflect off the first layer of glass, making them appear clear.

The blue film hates water, and contracts when exposed to it, which is why so many blue lenses appear badly tarnished. The seal around the rim of the glass lets go and water gets in. I pulled a tarnished headlight apart outside on the picnic table to see how they went together. A light shower came over and very soon the blue film had wrinkled up terribly and smelt awful.

It's an interesting topic, hopefully someone can come up with some conclusive evidence as to why the different colours and why they either started with blue headlights and went to clear, or the other way around.