system
Given the following post, respond as if you're commenting on Reddit:
human
How do they polarize glass?

Evert time i google how polarized glass is made i get some non-technical stuff about how they are good for fishing, reduce glare, remove horizontal light waves. One article mentioned something about iodine crystals but didn't elaborate.

I just want to know how they treat the glass to get the polarization effect.
gpt
There are many different ways, one is simply placing a PVA (poly vinyl acetate) foil on the glass. This material approximately has the consistency and thickness of plastic wrap. The manufacturing process begins by heating and stretching PVA to five times its natural length, making it even thinner. This lengthens PVA's long chain molecules, causing them to align. The stretched PVA is then dipped in iodine solution. The iodine is absorbed into the molecular chains forming long grids of parallel, darkened lines that are not visible to the human eye. The film is then dyed to the color of the desired finished film. The darker the film, the more polarization it provides. In the last step, the film will be applied on the glass.