Over the years, I have noticed that many of the vintage gauges made from plastic take on a yellowish tint. This is likely from age, sun light, and ozone. Recently, I began polishing some of my vintage Voit gauges with a polishing compound developed for clear coat car finishes. As you can imagine, the grit is extremely fine. I would estimate it to be around 3,000 grit, as it takes even the most minute scratches out of clear coat paint. Given that the compound is so mild, it takes a bit of time and effort to make a positive impact.
Much to my satisfaction, I began working on a slightly yellowed Voit (Taylor) depth gauge that I obtained from Karl while at Silver Springs. After around an hour, I am very pleased with the results. To my tired eyes, it looks like new. The compound is made by 3M and is called Finesse-it II Finishing Material. It isn't cheap, but works great on motorcycle helmet face shields as well as your car or motorcycle's finish. The pictures speak volumes.
Greg Barlow