Quoted from razorsedge:
I believe some games do have off white there as specification. Turtles is a bit later, but 3 playfields I have are all the same shade of "off white" and very uniform, can't see how those areas were ever pure white. Straight White base is found beneath the off white, though.
I started scrapping some on the clear to see what I could see ( the bear went over the mountain )
Here is some light scraping with an Exacto knife. No change in color.
More scraping. Still yellow in color.
A lot more scraping and some white looks like it is showing up.
More scraping and some white is looking at me. The white part seems a little thin and I have to remind myself that the white, along with all play field colors, is silkscreened ink and not paint.
I did not want to stop there so I did one more scraping along the side of this old QS play field. Eventually, it goes to white. So, if the white areas are showing yellow due to clear coat yellowing, then these is no way we are seeing the vibrancy of the original colors when the pin was new.
I guess this could be a equivalent to some of those "old Master" paintings in the old world that are being cleaned up by the curators of those items.