Sometimes a new post is indicated. The bow is as essential to the instrument as the player or the strings. The stick must be kept free of rosin build-up. Wiping with a soft cloth after each playing session will do nicely. The bow must be loosened after each use, or it will stretch hair and lose camber.
Proper camber is indicated when the hair just almost touches the stick when loose.
Rosin should be used sparingly and only if the bow slips or doesn't grip. Failure to rehair when edge hairs are lost will result in a permanently warped bow which will have to be straightened. Bows left unused in the case for a few days or a few weeks are prime fodder for the bow hair bug. It is really the larva of the carpet beetle, and thrives on rosined hair and only in the dark. If the bow is used every day, the bug will not eat the hair.