We have a variety of different hair that we use to rehair bows. Pictured is an example of three of our middle textures which we refer to as Golden White, Grey and Chestnut (from smoothest/lightest to most coarse/darkest).
What is the difference?
We sort the hair by texture and the result is a strong relationship between color, diameter, texture and elasticity. Hair with less color is thin, smooth and elastic while hair with more color is thicker, more coarse and less elastic. Grey and Chestnut hair are more textured and offer more grip than white hair. White hair is more elastic and produces a smoother sound with less surface noise.
Why different colors?
Hair color is determined by the amount of melanin (the substance that produces pigment) in the hair. The more melanin the darker the hair. To accommodate the extra mass the hair increases in diameter and the texture becomes more rough. Darker hair also absorbs more UV light which makes it less elastic. While texture and diameter are correlated with color, the hair is not actually sorted by color, it is sorted by feel. Sorting by texture is much more reliable and results in more consistent batches that happen to look alike.
Should I be using darker hair?
Grey and Chestnut hair are more textured and offer more grip than white hair. The trade-off is decreased elasticity and more surface noise. Players who like darker hair prefer grip over finesse. You gain the ability to grip the string even in adverse conditions but delicate phrases, lyricism and spiccato may suffer.