Hi Carl, Mac and all, Whatever material is used cannot have any coating over the printing, nor any ink sticking up, nor any printing impressions as they all disturb the shadow line a lot at such oblique edges. It must also be very smooth, of a uniform thickness, quite opaque and very bright, maybe flourescent as well as really water and weatherproof (both the material and the inks). That is why I have tried Sublimation Dye Transfer Printing and Tyvek. The tests I ran with Tyvek used cooled Tyvek and a heated dye transfer sheet on our transfer press. Tyvek does melt at normal dye transfer temperatures. I've mounted it around a very smooth, polished stainless steel tube, slotted on the back side for the tensioning. It worked well to start with but has faded and I'm now told by Dupont that under constant weather exposure Tyvek 10 ( the hard stuff ) is only good for maybe 6 months. All the outdoor sign people I've talked to. ( Not many, we are in a small town ) seem to use various Vinyl sheets, including Billboards. I guess it is like some Marine Epoxy I bought, advertised as Waterproof. The small print says not for constant immersion in water, nor aquarium usage.
Some of you folks that live in larger towns with many printers could maybe check this out for us. If so, thanks in advance. Edley. > Hello Mac, > > I have an idea that you might want to try. It appears that what may > work is a very thin protective coating. The laminations and overlays > are probably all quite thick. You could make your sundial from > regular paper and spray a clear coat on the surface. The protective > coating used on cars might work. I don't know if you can buy this in a > spray can but perhaps you may know someone at a body shop. If they > were willing to spray a couple of sundials for you it could be done so > one has a very thin coating and another a thicker coating. This would > give you an indication of how the thickness of the clear coat affects > the terminator. > > There is also a special clear coat that can be sprayed on outdoor > murals and allows you to remove graffiti. But I know this stuff is > quite expensive. > > Best wishes, > > Carl > > -----Original Message----- > From: Mac Oglesby [mailto:[EMAIL PROTECTED] > Sent: Friday, May 18, 2007 6:25 PM > To: Carl & Barbara Sabanski > Cc: Sundial List > Subject: RE: Waterproof papers > > > > Hi Carl, > > You wrote: > > >If the cylinder azimuth sundial was printed on normal paper and then > >laminated that would give a durable dial. > > > Thanks for the suggestion. > > Alas, in my tests, an azimuth cylinder sundial with a laminated paper > dial face does not have a good light/shadow boundary. I have tried > laminations and overlays of different thicknesses. It seems that even > a very thin layer of any transparent surface seriously deteriorates > the terminator. > > A vinyl dial face, as printed by a commercial sign shop, seemed like a > great way to create a durable azimuth cylinder sundial, but the > terminator is weak. > > Best wishes, > > Mac > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial >
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