More C&S #9 interest

Yesterday, I showed the Helen McGraw Tatem film, which is a VHS copy of C&S NG operations from the years, 1934-1937 it was interesting to see these films (the only ones I know of) of C&S NG operations. Ms. Tatem lived in Bailey and shot MP film of fascinating C&S NG operations in the final years. Incredible images, albeit not perfect.
In one shot, she focused her camera on #9 on the last run. I believe it was stopped atop Boreas Pass, and she focused her camera on the side of the cab and shot a CU of the "9".
Last night I had two of my colleagues over to view the film. Like me, they are experts in photography and lighting.
We have come to the conclusion that the "9" on the side of the cab is NOT paint. From the reflections, changing a little with the unsteady hand of Helen's camera...that it is plated metal, and would look in today's world like brushed stainless steel.
It could have been nickel-silver, worn rough with wiping off the soot and roughing the silver shine...or whatever. It IS isteresting that this
number...is to us....not paint but purposely applied plated metal. Speculation might be that since #9 was the premiere engine, and 90% of the time, pulled train #71 to Leadville, that somebody in the shop...took it upon himself to give #9 some special recognition. Interesting!