An extremely dumb question: Ridges on binding

[putnamm]

I've made one mandolin. I used ABS binding. Never again.

But it was perfectly smooth. For my next build I'm using celluloid binding, which I ordered and recently received. I noticed it has ridges all along it.

Literally the only mandolin I've ever owned/played/held is the one I made myself. So it's the only frame of reference I have other than the Internet. So forgive me for what may be an incredibly dumb question but, what purpose do these ridges serve?

[rcc56]

If you are using "ivoroid" binding, the "ridges" may be a color grain that was put into the material to imitate the appearance of natural ivory.
If you are using pure white binding, there may be ridges that were left over from the cutting process.

A little roughness in the glueing surface of any kind of plastic binding can be good for adhesion. Any roughness on the public side can be sanded out prior to finishing the instrument.

[HoGo]

Perhaps they are saw marks from cutting the strips? Picture would help... Where did you buy it?

[Skip Kelley]

Ridges on the binding or is it ripples in the binding? Picture please.

[putnamm]

Thanks, everyone, for your follow-up, questions and offers to help. Upon further inspection, rcc56 was correct that this was a coloration or effect placed on the binding. It is, in fact, entirely smooth. So no actual, physical ridges in the binding at all.

[rcc56]

The material you have is called ivoroid. The coloration is a simulation of the grain lines that are usually found in elephant ivory.
It is similar to the material that was used on Gibson mandolins in the 'teens and early twenties. Martin used it on all guitars style 28 and above through the early 1960's.
It is also seen on most modern instruments that use light colored celluloid bindings.

Pure white celluloid is also available, but I do not see it used much in modern era instruments. I know of only one supplier who carries it.