Over my unimpressive not much over 2 years of experience on the violin I've heard much talk about the wood that bows are made of and how the different woods or composite materials effect the playability, sound quality of your violin.

However, I've not heard anything on our forum of the part of the bow that actually causes the bow to to make any sound what so ever. You can drag that piece of wood or composite material over the most expensive strings that you can buy all day and make very little or no sound at all.

Everyone seems to have forgotten about that that piece of 'horses' butt' that is that is stretched between the ends of the bow. And after some research I've found that the quality of the horse used on a bow is as equally important as the material that supports it. And I have personally become to believe that it may be even more important than the material supporting it.

When you have been looking at buying a new bow have you ever considered or even heard of bow hair with names like stallion, mare, Siberian, Australian, Canadian and so on. I would guess, never. Most may have heard off Mongolian as it's a name for bow hair that seems to be bandied about 'willy nilly' as a description on the likes of eBay.

Regardless of the hair type or source, I've read that many believe that the most important factor determining the quality of bow hair is how well it has been sorted, or graded. Only a relatively small number of hairs from each tail are suitable for bow hair.

The grading process involves pulling strands of horsehair through human fingers to feel the thickness, roundness, stretchiness, and strength of each hair. Hairs that are kinky, vary in thickness, or have knots, splits, deposits of crud, or other defects get sorted out and saved for use in paintbrushes. Sorting is done by hand which is an expensive, labor-intensive process. This helps to explain prices that can vary anywhere from $75 to more than $600 per pound wholesale: less expensive grades of hair are sorted “en masse” to eliminate only the most obvious bad hairs, while the most expensive bundles have been carefully selected.

Even the gender of the horse that the hair comes from seems to matter.

I've read that mare hair is a bit thicker and more aggressive than stallion hair. “Color drift” is the industry term that describes the variation in color from one end to the other in a bundle of hair. The whitest hair, with very little color change throughout the length, is often bundled and sold as stallion hair, while hair that has more color drift to a darker color is sold as mare hair.

And then just to complicate things a bit more there is the relationship between bow hair and rosin.

There are many who believe that even with the many different types of bow hair, it’s actually the amount and brand of rosin, and not the hair, that has the greatest affect on the feel of the bow and the sound that it pulls from an instrument. But that's a whole different topic and I feel that it's one that has been well enough covered on this and many another forum.

To me there seems to be just too many variables in 'what is a good bow'. The more I read the more confused I get.

I've not included any graphs or charts because I don't really understand most of the ones I've seen 

So I think I'll just go and pick up my bow of unknown origin and rosin it with my block of mysterious rosin and go play a tune and try not to think about it.

What you hear coming from a bow is only as good as the player after all. You could give 'me' the most expensive and best made bow on the planet and I'd muck up the tune. 

(source) generally plagiarised from all over the internet