Hi Steve, I agree with Roger; opaque is far better than translucent. Also, as he says, it is the shade or tone that really matters; try cards in different shades to see what works best in your light. I would suggest that colour is important from a design perspective; what other colours does it have to blend with? Such as the colour of your house, for example. But check with the plastic sheeting manufacturer, UV resistant means that the plastic will not decay; but will the colour last? When I painted the dial on the front of my house I checked the paint manufactures details as to the permanency of the colours and used the ones with a longer colour life.
With best wishes, Jackie Jackie Jones 50° 50’ 09” N 0° 07’ 40” W -----Original Message----- From: sundial [mailto:[email protected]] On Behalf Of Roger Bailey Sent: Saturday, February 25, 2017 3:38 AM To: [email protected]; Steve Lelievre Subject: Re: Dial face colouration Hello Steve, Consider translucence, the diffusion of light on the substrate. This semi-transparency diffuses the contrast between light and shadow. Plastic, glass even rock can be translucent and compromise the shadow on a surface. I have noticed this problem with high quality Carrara marble, smoky glass, porcelain and plastic slabs. An opaque, non-reflective surface like grey oolitic limestone is best. Colour is just a distraction. The contrasts of shades of grey from bright sunlight to dark shadows are our medium. Roger Bailey Walking Shadow Designs -------------------------------------------------- From: "Steve Lelievre" <[email protected]> Sent: Friday, February 24, 2017 10:04 AM To: <[email protected]> Subject: Dial face colouration > 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 > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 2016.0.7998 / Virus Database: 4756/14015 - Release Date: > 02/24/17 > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
