Dear Steve I do not know how you are planning to cut and fabricate your plastic sheeting. But if you have not looked, there are many many bi-colour double layered UV resistant acrylics used by the sign-writing industry. See, for example, https://www.engraving-supplies.co.uk/laser-materials/trolase.html <https://www.engraving-supplies.co.uk/laser-materials/trolase.html>. The advantage of these materials (or single colour acrylics) is that they can be either cut and engraved with great precision and minimal cost by laser-cutting. All you need is a good .pdf graphic made to appropriate specs for your laser-cutter. Typically, text - which is raster-engraved - will be one colour. While vector lines and curves will be lines of a certain thickness and of different colours (one colour for a cut, others for different depths of engraving).
One of the great advantages of the laser cut approach is that you can try endless designs cut/engraved on cardboard - costing virtually nothing, before committing to your more expensive final material. Laser cutting is cheap these days and if you live anywhere near a big city, you may find that there is a 'FabLab', where you can go and do it yourself - see www.fablabs.io/labs/map <http://www.fablabs.io/labs/map> Having started designing sundials by laser-cutting in Cardiff University's FabLab - I am now actually employed there part-time to teach others in laser-cutting. So I am happy to elucidate further if anyone is interested. cheers Kevin > On 24 Feb 2017, at 18:04, Steve Lelievre <steve.lelievre.can...@gmail.com> > wrote: > > 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 >
--------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
