Would binding material for a Martin 18 style guitar?

[WayneLiao]

I was wondering what are the traditional binding materials used and during what years for an 18 style Martin? I've heard of tortoise, rosewood and I think even some type of black material (ebony or boltaron?); not sure when or why they used each different type. Thanks!

[mercy]

Now they use a black type of plastic. It looks yucky but does a good job of protecting the edges.