30 volume developer on dark hair: A chemical solution mixed with hair bleach, 30 volume developer is a dynamic hair treatment used to lift the melanin in dark hair, opening up its cuticle and allowing the bleach to penetrate more deeply.
Its relevance lies in enabling dramatic color changes from darker brunette shades to lighter blonde, adding depth and dimension to hair while reducing brassiness. The key historical development in hair bleaching came in the late 19th century when hydrogen peroxide was introduced as a safer alternative to harsh chemicals like ammonia.