Re: Porcelain Sundials
Message text written by Frank King John Carmichael explained that the biggest oven that his suppliers use will accommodate a maximum size dial of 46 square. The Margaret of Antioch dials are over twice that size. I wonder whether Brookbrae could still do a job that big. If so, they may have a customer! I don't know. There have been changes at Brookbrae over the years. Earlier in this thread John Davis referred to an enameller that he used and I seem to remember that it used them at least partially because they were one of only a few who could accommodate the size of dial that he then had in mind. I am sure that he will read this and will explain the issues. I am actually unsure of the needs of the technology here because the problem is supposed to be the paucity of ovens of a size that can take the metal bases. However in a very extended restoration of a vintage car (it's 42 years since I last drove it!! ), some years ago I needed to get some replacement mudguards repainted. I then discovered that the originals had been stove enamelled and in trying to be authentic I have found no difficulty in getting that done first with a matt-grey priming enamelled layer and later with a gloss one. Are the ovens used for stove enamelling car parts (the ovensI used for my mudguards were of a walk-in size) the same sort as those used for artistic and enamelled signs etc? I have heard that stove enamelling needs a higher temperature than powder coating It would be nice to know if a combination of the two technologies can be used to solve the problem you have. Patrick --- https://lists.uni-koeln.de/mailman/listinfo/sundial
Re: Porcelain Sundials
Hi Frank et al, The Houghton Hall sundials were made by Vitramet Europe Ltd. (http://www.vitrameteuropeltd.com/). I notice that one of the dials actually features in the photomontage that heads their homepage. Although Vitramet have some facilities in the UK, the Houghton Hall dials were actually enamelled in Mexico(!) because of their size (1320mm diameter or around 53.5). I only had to deal with the UK office, I'm pleased to say. I don't know how much bigger they could go. One nice feature is that the gold lines feature real gold particles which are ground up in the paste enamel and then fired in - they do have a cheaper option though! One of the dials (the N face) had to be in two pieces to allow it to be assembled around the original 1727 gnomon which is fixed into the stonework behind the dial. Thus if you wanted to make a dial which was bigger than Vitramet's oven, it would be possible to assemble it from separate panels mounted edge-to-edge. Regards, John D -- Frank King [EMAIL PROTECTED] wrote: Dear Patrick, Your short message is a mine of information... I am fairly sure they (the dials on St Margaret of Antioch's Ch) ARE enamel! You are quite right to refer to this place as the Church of S. Margaret of Antioch and, likewise, I should have referred to the Collegiate Church of S. Peter in Westminster rather than the vernacular Westminster Abbey! I must try harder! As far as I know, the latter has no dials (though I put one in the street close to its Chapter House) whereas the former has four. Even more interestingly you say: Yes, they are enamel They are huge too - 8ft 6ins in diameter. This measurement raises further questions. John Carmichael explained that the biggest oven that his suppliers use will accommodate a maximum size dial of 46 square. The Margaret of Antioch dials are over twice that size. I wonder whether Brookbrae could still do a job that big. If so, they may have a customer! Frank --- https://lists.uni-koeln.de/mailman/listinfo/sundial --- https://lists.uni-koeln.de/mailman/listinfo/sundial
strange longitude
Greetings fellow dialists, Mea culpa and apologies to all. In my initial message I gave the co-ordinates of the Hawkshead dial (Lat 54 deg. 22 min. 10 sec. and PL 35 deg. 43 min. 40 sec.) but omitted to say that between PL and 35 deg. the word Long occurs. I am most reluctant to let go of Gianni Ferrari's brilliant polar latitude solution. I should also say that beside the cited latitude there are some other numbers but I am fairly sure from what I can make out in my photograph that they refer to the declination of the dial plate away from south. It is strange how nearly the two values add up to 90 deg. Once again my apologies to everybody who has contributed to this problem for not giving out the full details, and will you kindly attribute this omission to my too many birthdays. Frank 55N 1W -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.463 / Virus Database: 269.5.9/773 - Release Date: 22/04/2007 20:18 --- https://lists.uni-koeln.de/mailman/listinfo/sundial
RE: Porcelain Sundials
Message text written by John Carmichael Porcelain is a vitreous enamel which means that it is composed of glass frit (fine dust sized particles of glass). It requires HIGH firing temperatures of about 1500 degrees F. and kiln-type ovens. But the enamel and powder coatings used on car parts or lawn furniture is more like traditional paint and is baked at much lower temperatures- about 350 degreesF. Thanks for that John, pretty clear one doesn't want the vitreous/porcelain stuff on a car because it must shatter if bent! However, the interesting thing is whether or not the fired enamel paint and powder finishes would be just as good as dial finishes. I shall ask Chris Daniel (who is not a member of this list as far as I know) about what he thinks the finish was on St Margaret's. Patrick. --- https://lists.uni-koeln.de/mailman/listinfo/sundial
