For those curious about it, bow hair comes in a variety of natural colours. (I'm not going to waste time talking about dyed hair, it's usually garbage.)
White hair: comes in many different grades. The "best" is Live Stallion hair, which, as its name implies, comes from live stallions. This tends to be very fine hair, and very white, and has the characteristics many people find desirable in white hair; smoother, brighter, etc. A step down has hair from both mares and stallions, is a little bit coarser, not as white in colour, but can still be really great hair, and have that "white sound"
Keep going, and you end up in coarser still whites, and then silver - silver/grey hair (which people often confuse for salt and pepper, which is an actual blend of white and black hair) then chestnut, then into mixes closer to, and finally black.
Black can be darker sounding, it has a little more attack, they prefer it for orchestra playing, there's a little more of a "sizzle" or gritty sound to it etc.
The various shades in the middle, tend to be a blend of characteristics, and it's entirely personal preference as to which end of the spectrum you want to lean towards. I really like "Fiddler's" hair on a bass bow, which is a really coarse white, and sits right in the middle of the spectrum, just a little bit closer to white than black.
With all that said, a LOT of shops carry the best white they can get their hands on, something a little step down from that for some of their cheap bows, black for bassists, and occasionally a silver/grey or in really rare cases a good salt and pepper blend. Most players don't know that there are so many options, get confused/scared by choices, and just want white or black anyway.
Sorry for being long winded. Almost done, GOOD NEWS below.
Lynn Amour Hannings (a fantastic bow maker and educator, and a bassist as well) carries eight (8!) varieties of bow hair. I would really recommend going to/shipping your bow to her for a rehair because she really does great work. BUT if you have someone local who you really love who doesn't carry the type of hair you are interested in trying, and is ok using someone else's hair (all questions you need to ask before hand) Her hair is all really great quality, AND you can buy individual hanks (enough for one bow, instead of a pound, which is enough for around 100 bows or more) directly from her.
Stay away from anything green or blue or purple (I had to do a rehair for a kid who wanted it, and it's absolutely horrible to work with) but there is a NATURAL rainbow of hair colours out there. Feel free to explore!
