AB Rosin is a dark rosin for cellos. In the latter half of the nineteenth century, Miss Amy Birch (AB) perfected a rosin for her personal use. After long experiments, she developed a compound which was 'kind to the bow,' unaffected by extremes of temperature or humidity. Because of it's non-clogging characteristics, her new rosin helped to produce volume and purity of tone. It was first commercially marketed in 1896, at the behest of Miss Birch's professional colleagues.