Dark rosin is softer and is usually too sticky for hot and humid weather—it is better suited to cool, dry climates. Since light rosin is harder and not as sticky as its darker counterpart, it is also preferable for the higher strings. … “Lighter rosins tend to be harder and more dense—a good fit for violin and viola
Dark rosin’s soft, sticky nature is not ideal for hot, humid climates as it can clump up. In addition to diminishing sound quality, darker rosin can also make a mess on your bow, strings, and the instrument’s body. Most violinists use lighter- to amber rosins to achieve smoother sounds, while bass rosin is on the softer, stickier side to provide increased friction and richer tone. Innovative products, like Magic Rosin, offer superb grip, clear complex tone and fun designs using purified pine rosin that yields a completely translucent product.
Always use a soft cloth to wipe off strings and the instrument body after every use to prevent destructive rosin build-up.