Hi Frank & Tony: Long ago I had a discussion with the owner of the stone quarry in Utah where I get most of my flagstone. He said something that stuck in my mind ever since. He said: "Stone is free. Its cost comes from moving it". No truer words were ever said!
Stone is pure weight and mass, and it gets damaged easily. Most of the slate deposits in the US are located in Vermont (so I hear). I live thousands of miles away in Arizona. It just costs too much to have it expertly cut, crated and shipped to me so far away. Also, my sundials require very thick stone 1 1/2 to 2inches thick- even thicker than Frank's beautiful dial. Most stone used for commercial purposes- countertops, wall coverings and pool tables is much thinner. So I need special cuts too. I have also heard that US slate is flaky- sort of like mica. British slate seems quite solid without flaky layers. But I did manage to get a sample of slate from Jack Aubert long ago. I did extensive tests to it using my cutting tools and techniques. I love the way it performed. It cuts and engraves beautifully and easily using my high speed diamond burrs. Oh well... -----Original Message----- From: Frank King [mailto:frank.k...@cl.cam.ac.uk] Sent: Saturday, March 20, 2010 9:24 AM To: John Carmichael Cc: 'Frank King'; 'sundial list'; frank.k...@cl.cam.ac.uk Subject: Re: Equinoctial Announcement Dear John, Many thanks. Several people have asked the same question... > Is that real gold leaf gilding? Yes, it is real gold leaf. The nodus and nodus support are made of brass but they are gilded with gold leaf in the same way as the sun, and the Babylonian Hour-Lines, and associated numbers. I wanted to try gold-plate for the nodus and nodus support but the advice given was that it is impossible (or at least very difficult) to gold-plate brass. Next time I shall use stainless steel which seems to be much easier to plate with gold. [Aside: the explanation about gold-plating brass being difficult is that the zinc content of brass interferes with the plating process. I am not wholly convinced because you can have brass-plate easily enough!] > I sure wish we could get nice big slate > slabs like that here! There are still some good slate quarries in the U.K. The noted ones are in Cornwall, in Wales and in the Lake District (NW England). [Aside: there is also good slate in Spain and in Belgium if you look hard!] Slate is quite a common building material here, especially for roofing but also for kitchen floors and worktops. One problem with slate is that it is prone to contain Iron Pyrites (fools' gold) which looks quite nice when the slate is newly honed but, outdoors, it quite quickly turns to rust and discolours the whole slate. For plaques and sundials, one has to specify "monumental" quality slate. The Selwyn slate came from the Lake District and is in the form of a true ellipse whose major axis is 1065mm (42") and minor axis is 865mm (34"). The thickness of the slate is 35mm (1.4"). This means that the slate weighs about 71kg (156lb) which is quite heavy! If you picked up such a slab of slate on your next trip over here it would probably go over the weight limit of your hand-luggage :-) We all wore steel-capped boots and were very careful during the lifting! The nodus wasn't attached to the slate until almost the last moment. There are three long bolts through a brass base-plate on the back of the slate. This wasn't gilded. The guy who attached the nodus wore surgical gloves. We don't like finger marks on gold leaf! All the best Frank --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
