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GF clock question

Dave51

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Jan 13, 2021
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Hi folks new to this forum. I have a 1927 German Kienzle GF clock that runs perfect and sounds great. I was wondering if anyone has had to deal with clock hand shadows on old clock faces. My clock has a long history being over 90 years old but obviously must have sat unused for a extended period at some point. The minute hand is narrow so no shadow from it but the hour hand is the old spade or heart design and has left a shadow on the dial. It is clearly noticeable under good light conditions but less noticeable under low light conditions. The dial is brushed steel with painted numbers. The shadow is on brushed steel section. Science would somewhat dictate the dial is faded from exposure to UV light and the part that was under the hour hand was protected and is less faded causing the shadow outline. Another possibility would be oxidation but I tend to lean more to the UV light causing fading. Would exposing just the shadow to high UV/sunlight reduce its appearance? Say cut a cardboard cover for the dial and a hole cutout for the shadow and just leave in the sun for a few days to see what if anything happens? The dial is original so don't really want to change it. Also just using the clock should over time reduce the shadow but that would be a slow process. Any ideas? Thanks and stay safe.

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new2clocks

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Welcome to the forum.

Your questions may receive better exposure in the Clock Repair forum.

If you click on the REPORT button, you can request that a moderator move your post to that forum. Only a moderator can move a thread.

Please do NOT start a new thread on the same subject. This only causes confusion.

Regards.
 

howtorepairpendulumclocks

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Dec 18, 2020
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Sorry I don't have the answer here other than to say this is a cool question. You need a chemist! Clock dials in my experience are electro-chemically silvered and then lacquered. If this is the case, you might have quit a complicated question/answer. It got me looking at articles on darkening of silver in light which is I presume a totally different process from darkening due to the presence of sulphur. You also have the possible degradation of the lacquer thrown into the equation. fascinating to se whether the mask idea works. Was the clock in a city or urban environment re sulphur? Good luck and hope a chemist steps in to elucidate!

 

Dave51

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Jan 13, 2021
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Thanks for your comments. It got me thinking again about exactly what the dial is made of. I had checked it with a magnet and assumed steel. But another look from the back this time shows a pressed steel backing. Plus no steel backing close to the center whole. So checked again with a magnet and does not stick near the center of the dial. So it could be brushed aluminum or plated brass. The rim around the dial is brass but the dial itself seems to be independent from the rim. Maybe glued to the steel backing? Not sure. I have a UV light box I built years ago for changing the colour of old glass. I may give that a try if no one comes up with a better idea. Take care.
 

chimeclockfan

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Never seen a hand cast a shadow like that on any dial before. Kienzle's silvered dials went back and forth between brass and aluminum backings. Tacks and punches were the usual way of keeping things together.
 

chimeclockfan

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i would imagine the silvered coloring behind the dial is what the entire dial used to look like prior to UV exposure.
 

Dave51

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Jan 13, 2021
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Never seen a hand cast a shadow like that on any dial before. Kienzle's silvered dials went back and forth between brass and aluminum backings. Tacks and punches were the usual way of keeping things together.
Thanks I think this is aluminum. I can see circular machine marks across the entire dial. I will probably try the UV light treatment first if that doesn't work then maybe its oxidation of the aluminum and an aluminum cleaner may work. The UV light I don't think will cause any damage to the dial. A cleaner might. Personally I think its part of the history of the clock and never paid much attention to it over the years.
 

Dave51

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Jan 13, 2021
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i would imagine the silvered coloring behind the dial is what the entire dial used to look like prior to UV exposure.
Possible but the dial is very bright silver in colour where as the shadow looks more light grey. The hands are steel and if the dial is alum. Possible it may be a reaction to dis-similar metals rather than UV? If so a cleaner may work. Although the walnut case also shows signs of sun lighting on one side which did led me to the UV conclusion in the first place.
 

bikerclockguy

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Jul 22, 2017
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I would try some Simple Green, lightly misted on an old t-shirt, so that you don’t get any runs or drips. I’ve found it works well with aluminum, and I’ve he had any problems with discoloration from using it. If that doesn’t do the trick, you might try some Renaissance Wax.
 

Dave51

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Jan 13, 2021
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I would try some Simple Green, lightly misted on an old t-shirt, so that you don’t get any runs or drips. I’ve found it works well with aluminum, and I’ve he had any problems with discoloration from using it. If that doesn’t do the trick, you might try some Renaissance Wax.
Thanks will give it a try since I have them here.
 

shutterbug

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You might try Cream of Tarter too. Just on the area that shows the shadow.
 
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