Ivory and Ivoroid

[Robert Hull <RHULL@PALVX.NMSU.EDU>]

Can someone enlighten me as to the history of plastic ivory
substitutes? Some of the early 20th century instruments I've seen have
tuning keys or other components that are white (yellowed) and grained
like I would expect of ivory. But there is usually a tell-tale mold
line that suggests the part is molded plastic. How far back does this
technology go? When did the manufacturers start using ivory substitutes
on their lower-priced instruments?

I've also read that elephant ivory has grain of a certain direction,
whereas walrus ivory has a distinguishably different grain orientation.
Any comments?

Thanks for the assistance.

Robert Hull
New Mexico