Hi Dan,
Many choices exist depending on what kind of maintenance is expected, exposure to public indignities and whether you seek a natural patina. Numerous brass and bronze alloys are possible depending on price and availability. Flat plate can easily be cut with waterjet so you don’t need leaded brass. Outdoor bronze sculptures typically get an application of a wax, usually after a chemically applied patina, but wax must be reapplied periodically. Natural uncoated patinas can be unpredictable depending on local climate, atmosphere, handling etc. and could run onto the stone. They can be waxed after reaching a sought-after appearance. If you don’t like how a patina works out it’s easy to sand it off and start over. 316 stainless steel is commonly used outdoors and has added molybdenum for corrosion resistance and can be bead blasted for matte appearance. Probably not the best option for a replica. It’s very rust resistant but not rust proof. It does have the great advantage of being more vandal-resistant than softer metals. Many metals can be high-temperature treated with tough ceramic coatings after machining and bead-blasting for a matt finish, such as titanium nitride which has a gold appearance and was once of the first to be used on drill bits, now there are many others. This type of custom work can get expensive although it’s done for special motorcycle exhausts and similar projects. I would probably go with a traditional chemical patina on bronze and keep it waxed. Of course, many dials are eventually neglected and there is no guarantee anyone will continue to maintain waxing. …Tom Kreyche From: sundial <sundial-boun...@uni-koeln.de> On Behalf Of Dan-George Uza Sent: Saturday, April 30, 2022 8:55 AM To: Sundial List <sundial@uni-koeln.de> Subject: Metal gnomons Hi, Iron rusts and brass changes color, but what about different metals used as gnomons, pros & cons? What would be the appropriate choice of material for a replica of an 18th century cubical multiple sundial? It should ideally come as an industrial sheet ready for cutting and also not stain the limestone face. I like the metal in the attached photo (Sundial Atlas CH 000247). Do you know what it is? Thanks, Dan Uza
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