My experience is use a mat finish sand color. It
also matches with nearly every colorscheme.
At 03:25 26-2-2017, Michael Ossipoff wrote:
It seems to me that Steve's question has been
mostly disregarded rather than answered.
Not having experience with translucent
dial-faces, I didn't know about their lack of
accuracy, and I certainly can't disagree with
what two people have said about that.
It means that the advantage of a translucent
dial, for omnidirectional reading, comes with a
disadvantage of less precise accuracy.
But of course a high-mounted dial intended for
relatively distant reading might not be as
concerned with fine accuracy as with
omnidirectional viewing. And so translucent
dials for all-directions viewing certainly aren't ruled-out.
Steve's main question was about the choice of
dial-face hue, saturation and brilliance, for
easy and safe dial-reading. It seems to me that
Steve's question has been mostly disregarded and
discounted rather than answered.
I lied.
I said that I can't speak from experience on that matter.
But my experience with a few paper-on-cardboard
tablet-dials is sufficient to say this:
From my experience, I can say that you
definitely don't want a white dial-face.
As I said, my first dial had a white dial-face.
After that, I switched to brown, which was a big improvement in usability.
I suggest brown instead of white.
Someone implied that, the more contrast (between
light and shadow), the better. Not so, when the
dial-face is too white to look at in bright sunlight.
As for gray: Gray reflects the visible
wavelengths in a relatively equal mix, resulting
in no perceived hue. If some hues are (at least
relatively) to be avoided, then obviously gray isn't what you want.
At each end of the visible spectrum, there is,
of course, radiation that isn't visible.
Infrared (IR) and ultraviolet (UV).
 One possible disadvantage of that is that,
when you don't perceive it or its intensity,
then of course you could conceivably get a
dangerous amount (accutely or cumulatively) without any perception of it.
For example, never look at the sun when, due to
a haze, or due to the sun being low in the sky,
the sun doesn't look bright. You don't have any
perception of how ingtense the UV or IR is. It
could burn your eye without any feeling of
discomfort. (I don't know which of those is more
dangerous, but there have been official warnings
to never look at the sun when it seems less
bright due to haze or low altitude.)
Aside from that, there's been evidence that,
when people spend a lot of time outdoors, in
bright sunny climate, then many years of
exposure to the bright blue light can cause some
long-term cumulative damage. So maybe blue isn't the most desirable hue.
Yellow, beings the complement of blue, looks
yellow because it absorbs blue, removes blue from the light that it reflects.
Also, yellow isn't particularly close to either end of the visible spectrum.
Brown is defined as:
"Any of a group of colors between red and yellow
in hue, of medium to low brilliance, and of moderate to low saturation."
Then, dark brown would be brown with
particularly low brilliance--a desirable
attribute for a sundial-face. Might that be the best color for a dial-face?
Tan is defined as:
"Light yellowish brown."
...suggesting more brilliance than brown (but
surely a lot less than white), and enough
saturation to be perceived as yellow, which seems a good thing.
Brown, especially dark brown, or maybe tan,
sound like acceptable colors for a dial-face.
By the way, beige is defined as:
"A variable color averaging light grayish yellowish brown."Â
Sounds like tan, but with distinct grayness,
lower saturation, making it probably less desirable.
In my previous post I said that I bought brown
construction-paper, but didn't use it, and,
instead, just marked the hour-lines on the
corrugated cardboard instead of using paper.
Actually, I probably did use the brown
construction-paper. It looks better of course,
and it allowed me to conveniently use a
carbon-paper template that I'd prepared for drawing the hour-lines.
Maybe the plain cardboard dial-face would have
easier construction in one way, and less easy
construction in another way. Maybe I tried one
all-cardboard dial. It was a long time ago.
Michael Ossipoff
Â
On Fri, Feb 24, 2017 at 1:04 PM, Steve Lelievre
<<mailto:steve.lelievre.can...@gmail.com>steve.lelievre.can...@gmail.com>
wrote:
Fellow sundiallers,
Iâm 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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