Couple Questions on Advertising Knives

[dannyp]

I've been looking at old advertising knives lately and find it interesting to see all the different types out there. I know that a lot of the older ones had celluloid scales as it is obvious from the shrinkage near the bolsters. Are the more recent ones delrin or some other plastic and if so around what general time did they stop using the celluloid?

My other question is about the type with the cracked ice celluloid scales and the metal rim all the way around the edge. There are no visible pins, so are these just glued on or is there another fastening method that keeps them in place?