I am experimenting with Horse hair for railings on HMS Ready at the moment. Some are slightly wavy, but most given me were straight. One I ied had a split end {-) but clipped off easily. They seem to hold well with superglue and if from the right horse* are dark/black. They get thicker towards what would have been the follicle but on long lengths is not as noticeable.
*I got mine from a lady who parks her horse in a near field from work who was happy to help. If you know of anyone with horses then work your charms and see if they will let you have some after they have done maintenance on their horse/horses.