Unfortunately Steve there is no cure for sun fading. This is an antique and I would not do any thing to the cabinet but clean and wax it. You can reduce the fading effect but you will not like the method and I don't recommend it. What I do recommend is getting a good paste wax like bri wax. I would wipe down the piece with solution #1 and then wax it with the bri wax. Use the dark bri wax. This may help the fading. If this was mine this is all I would do to it. This piece from what I can tell as a true age patina so don't mess with it. If it really bothers you you can take aniline dye stain in walnut and wipe the faded area down and french polish the area. Then a coat of wax. I strongly recommend you don't do this. Lets keep this one as a museum piece please. I see some broken areas to the turnings also leave them alone. I hope I have answered you queation. Clean and preserve only here.
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