The shop never offered a "yellow" but the old Westinghouse stuff, if left in a lighted condition, would yellow, that's for sure. I bought (a couple of decades ago) 3 sheets of bone linen micarta (Had it made in Germany) for several projects I have/had going. I am now down to 1/2 sheet left. Below are a couple of examples of RMK "stuff" in bone linen. Let me know if this might be something you would like to order on a Randall.
Stay sharp, Capt. Chris
PS: Is does not appear to turn any darker...that I know of...CCS