This misunderstanding of the "2/3 orange" rear window actually being fully coated has got to be one of the most questioned things I have seen on the forum in a long time.
It just isn't that intuitive that another layer of partial tint causes the IR coating to reflect vs "pass through" the light that causes the interesting colored water beads.
For what it is worth, on my back window, when it is coated in dew, and I see the top 2/3 showing the (mostly orange) colors, if I stare closely as the lower 1/3 at a sharp angle I can see a little bit of the colored effect there too.
So even though many still seem to question/doubt it, I think it is probably true that all of those older rear windows are 100% IR coated and it is true that a different layer of (polarizing?) tint causes it to look like the bottom part isn't coated the same way.
So I think the colored dew drop effect is mostly due to 2 different layers of different kinds of coatings interacting with the light and water drops.
(Phew)
It just isn't that intuitive that another layer of partial tint causes the IR coating to reflect vs "pass through" the light that causes the interesting colored water beads.
For what it is worth, on my back window, when it is coated in dew, and I see the top 2/3 showing the (mostly orange) colors, if I stare closely as the lower 1/3 at a sharp angle I can see a little bit of the colored effect there too.
So even though many still seem to question/doubt it, I think it is probably true that all of those older rear windows are 100% IR coated and it is true that a different layer of (polarizing?) tint causes it to look like the bottom part isn't coated the same way.
So I think the colored dew drop effect is mostly due to 2 different layers of different kinds of coatings interacting with the light and water drops.
(Phew)