Fellow sundiallers,
I’m planning to make my next sundial from outdoor grade UV resistant
plastic sheeting. These come in a range of colours and I want to choose
one that works well for a sundial. Assuming I get the material
grit-blasted or somehow treated so that it not shiny, and leaving
aesthetic considerations aside, what light-related attributes should I
be looking for?
As anyone who has played with paper sundials knows, a white surface is
hard to look at in full sun, even if non-shiny; black would not show any
shadow. I need something in between: light enough to catch a shadow, but
dark enough to avoid glare in full sun. I assume that latitude has a
bearing on this, as the midday sun illuminates more strongly as we
approach the equator. In my case, the design latitude is around 45 N. My
dial will be about 25cm in diameter.
Are there any conventions or empirical guidelines, or even practical
experience, to help me choose?
Which properties matter? I quick read of Wikipedia suggests colours seem
to involve hue, saturation or luminosity (or parallel concepts in other
classifications).
Cheers,
Steve
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