340. How do window tints (for your car windows) work? Are they just polarized materials?
Some of them may be polarized materials, blocking horizontally polarized light, but most are simply absorbing materials that are embedded directly in the glass during its manufacture. Chemically tinted glass just darkens the sky be absorbing some of the light passing through the glass, regardless of polarization. It's not possible to chemically treat the glass to make it absorb only one polarization of light because that treatment would have to carefully align its molecules. In the plastic polarizing sheets, there is an alignment process (usually stretching in one direction) that lines up all the absorbing molecules.