If i may, I'd like to throw in a first hand, in the field, observation about the different effects colour has with telescope tubes and this was noticed on many occasions.
Several ( many ) years ago while out on observing nights with the astro club I'm in, it was noticed that my scope tube would be covered in dew while a fellow members scope would hardly be damp at all. Both scopes were old school cardboard tubed newtonians, my friends was a Meade dob, coloured white, whilst mine was a home made newt / dob, painted red.
So, as the materials of the scope tubes were the same and affected by the same environmental factors at the time, we were set up less than 5 metres apart, it could be construed that it was the difference in colours that was the governing factor in the dew formation on the telescope tubes.
If anyone has a better explanation I'd be happy to hear it. Sticking to white tubes these days but even they get dripping wet some nights, this is a very humid region after all so some price has to be paid for long nights in the field.
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