Has anyone else seen an increase in car rear screens that have a spotted pattern on them?

I'm assuming these are marks made during manufacture that become trapped in the glass during lamination?

Giraffe pattern type thing on mine

never heard of this

Giraffe pattern type thing on mine

Mostly I've seen on fairly recent VAG, Vauxhall, Toyota and Saab's.

I assume there's a proper technical name for it?

just found this - http://www.quora.com/Why-do-certain-types-of-glass-especially-on-vehicles-have-a-mottled-or-striped-polarization-pattern

Do you wear polarized sunglasses by any chance?

Do you wear polarized sunglasses by any chance?

I do now.

Not sure what the technical reason is, but polarized lenses bring out all of these patterns that are not normally visible to the naked eye.

I wear quiet strong glasses as am really short sighted and see this quiet alot on rear windows of cars, never really thought about it before just thought everybody could see it

Not sure what the technical reason is, but polarized lenses bring out all of these patterns that are not normally visible to the naked eye.

Honda's have a rainbow pattern.

Whilst I can see them all the time with my new sunglasses, I've been seeing them for a while. Using during periods of hot weather. My new prescription means I see them more often.

The pattern is visible beause the stresses in the glass cause partial polarisation of light passing through. Polarised sun glasses will make this effect visible. In stress modelling, before the days of computational dynamic analysis, models where made up in transparent materials and sujected to stress to see where the material came under duress within the part.

The pattern in the rear glass is caused by the tempering burners.

Chris