This is your banjo; the bridge does seem to be either bone or plastic:

This is very unusual. There is variation, but most normally a banjo bridge is made of maple wood with an ebony wood top. Bridge material, type of wood, quality of wood and bridge making techniques have a huge impact on the sound of the banjo. 

I would suggest, you start out with a normal maple/ebony banjo bridge. 

A good source for bridges in the UK is Eagle Music near Huddersfield. Here's a link eaglemusicshop.com/banjo-bridges

As best I understand... bridge impact? HUGE! bridge material? Maybe the wrong question.

Height effects playability and break angle. Weight and break angle together impact where (in frequency) your banjo's main voice is centered. Wood stiffness and shape (e.g., feet, cut-outs, etc.) add and subtract color above 2 kHz and, so, are important for attack, tone, timbre, and whatever.

Slot separation is a matter of neck width and your playing preference. There's always a usable range, and you'll develop a preference, which will depend in part on what playing techniques you use most.

For more than any sane person would want to know, try the April 2021 entries at http://www.its.caltech.edu/~politzer/

Slim Jim banjos makes and sells great bridges in the UK. They're £30 but we'll worth it. There's a choice of wood and height and he'll cut the slots to different spacings/string guages.

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Originally posted by davidppp

For more than any sane person would want to know, try the April 2021 entries at http://www.its.caltech.edu/~politzer/

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That first post of yours was really informative.  This second post is a very useful one for those here on the hangout.  I don't believe there are any sane people here, so this post is for everyone.  Too bad you weren't around in Stewart's day.  You could have offered your services as referred to in his last paragraph.

Very important. There is, for example, a significant sound difference in a standard ebony-top bridge and one of the same design that is all maple. If you’ve ever tried a carbon-fiber bridge, you know why wood is the standard.

rmcdow --Thanks, Rives, for the words of support. Actually, I just follow my nose and try to answer questions that come up. I enjoy the work. It's not unlike what I'd been doing for decades -- actually even better: I invent and perform experiments. But there's very little (none?) in it that wasn't already known to at least some serious builders and players in their own language. I don't imagine I could have changed Stewart's mind. Rayleigh was a Stewart contemporary, and Helmholtz just a bit earlier. Between them, they probably did more physics of sound, music, and instruments than anyone before or since.

Bone bridges are not uncommon in the larger scheme of things, they are traditional on Portuguese Guitars and probably the most common material for saddles on our typical guitars.

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Originally posted by Fathand

Bone bridges are not uncommon in the larger scheme of things, they are traditional on Portuguese Guitars and probably the most common material for saddles on our typical guitars.

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You're right of course, but I was limiting this to banjos… No idea how they sound on banjos, I'm skeptical however.

Many years ago, Banjo Newsletter had an article comparing 50 different bridge materials. If you could find that issue, it makes some interesting and surprising observations

There would be giant differences in bridges of identical design made from different materials —brass vs bone vs aluminum vs plastic, vs wood, etc etc. 

In terms of wood, the most common material for bridges, the kind of wood has a very large, but sometimes subtle effect on tone color and expressiveness, as well as other qualities mentioned before.

I've always wondered about a bridge made of crystal glass would sound like.

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Originally posted by KCJones

I've always wondered about a bridge made of crystal glass would sound like.

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If you look at the speed of sound through various materials, glass, brass, and hardwood, are remarkably similar, but having made one, I know that a brass bridge will sound vastly different than a wooden one, so I can't guess what a glass one would sound like. 

The velocity numbers make me imagine that density or some other quality of the material is more important than the velocity of sound transmission—of course, this is the province of David Politzer—I can only make uneducated guesses.

One interesting thing about this chart, is that "glass", which is probably regular soda-lime glass has a speed of 3962 m/s. while Pyrex (which is a borosilicate glass) has a speed of 5640 m/s. My experience at Corning Glass makes me very suspicious of this, and I think it's either an erroneous number or the soda-lime one is wrong—they are not that different.

Bone bridges would be doable but it's a heavy material compared to wood so it would have to be a thin design. Making one is not a pleasurable chore as the sanding stage heats up the bone and, well, the stench that generates is totally gross...

Crystal glass is not at all safe to use as a bridge material. The string slots will need to be ground in with a diamond coated bit. Due to the properties of glass, it will consider the string notches as uncompleted breaks. These future breaks will make themselves known as you're bringing the strings up to tension. At this point, Murphy's law is guaranteed to take over and ensure that the flying shards will hurtle direction your face. Probably Ken Levan, with his Corning experience, could suggest a better glasslike substance.

What Bart says is true—it would be dangerous.  Glass is a "perfectly flexible" material, which means that if you flex it it will either exactly return to its former shape or break.  99 out of 100 times, it breaks, and strings against a bridge would "point load" it—very bad with glass.

If you made the right design, maybe something like a half-tube, like the tubes slide guitarists put on their finger cut in half, tempered it, put it on the head with the round part facing up and had some way to make the strings stay in place on top without cutting grooves in it, it might work.  You could probably get someone who makes chemical laboratory apparatus ("lamp work") to make one.

Yes, those tiny shards of glass could come at you at mind boggling velocities. Definitely not a good thing to experiment with.

Bridge wise, there's a huge wide world of bridges available from beyond, yawn, the maple/ebony dogma from several bridge makers here on the Hangout.

Keep in mind that the ones available from Amazon, and places like that, usually are underwhelming, performance wise, and not always intonation friendly.

Just in case: I've retired from making banjo bridges myself as of December last year.

Do you have any recommendations on where one could acquire bridges of different materials? Thanks!

In the 19th Century, bridges didn't have caps (the harder top strip). They didn't have wire strings, either. (The two facts are not entirely unrelated.) If you're willing to forgo the cap business, all you need is a coping saw, sandpaper, and imagination. You can give them two feet, three feet, or four feet.

Then listen.

Of course, the caps impact weight and flex characteristics (the only things that really matter). But those aspects can be mimicked by wood choice and design. In the long run, softer woods won't hold up to steel strings as well as ebony caps.

Maple has nothing to do with dogma and everything to do with proven results from folks like Stradivari.
I've made bridges from all bone,ebony,brass,maple with a bone top,iron wood,lignum vitae and sycamore.
For best projection and depth of tone ebony on maple can't be beat.

My experience with bridges suggests that (at least for steel stringed banjos), the ebony-on-maple is a good starting point. However, since sound is affected by string tension, bridge material, bridge mass, bridge thickness, head tension, bridge design (e.g. number of legs, size of legs, architecture, etc.), there is no easy way to predict the "best" bridge for a specific banjo. I have several banjos on which I've tried various bridges. While ebony/ maple works well on all of them, on two, I am using homemade bridges made of purpleheart wood. It is very hard, more dense than maple, and my bridges are thinner than most stock maple ones. The weight is roughly 2 g. One is a two leg design copied from an old Gibson bridge someone showed on this sit a couple years ago. Bottom line, however, is that not all my banjos showed improved sound with these bridges, so trial and error remains the best way to select a bridge. Oh yes, I forgot the most important variable in the equation. What sounds good to me may may not sound good to you! Good luck.

No experience with them, so just throwing this out as another source: https://docsbanjos.com/bridges/

The weight of a bridge has a lot to do with the sound.That's why 2 bridges made out of the same board can sound vastly different from each other.
If they both weigh within .02 grams of each other they will sound the same.

I thought David Politzer's latest bridge study, linked above was very interesting, particularly the discussion of bridge design. I actually had the honor and opportunity to spend several Days with David doing testing on bridges. 

In 2014, I did an extensive study of bridge wood, weight, and design. Had I known he was doing this, I could have provided him with some bridges of different design made from the same piece of maple.

My own standard bridge design is a Roman arch, and I also tested several others, including the violin design, in which case I did not add a third foot, keeping it like the violin bridge.  They are all "smile" bridges, and cambered on the bottom as well:

They weigh different amounts, have different footprint areas, and of course, different designs.

Here are sound files comparing them, if you want to hear the differences:

I have listened to all of Kens bridge clips, and have decided that the speakers or my ears are not good enough to tell the difference from one bridge to another.
Perhaps with head phones there is a noticeable difference, or live in front of the banjo.