If you move a rosin-less bow across the strings of your instrument, you will hear....hardly anything. That's because rosin provides the friction required to produce sound when an instrument's strings are bowed. Made from tree sap (and often mixed with other ingredients to enhance sound production) rosin is an essential tool for string players.
You can learn more about how rosin is made in Sticky Business..., a post from Strings Magazine.
However, with all of the different rosin products on the market, it's not easy to determine which one is best for you and your instrument, or which brands are worth their notably higher prices. To make the best choice for you, learn all you can about different rosin types and make an educated decision.
Sometimes, it's not the rosin but the application technique that gets in the way of good sound production. Beginners should review, How to Rosin Your Bow, to ensure they're doing it right.
ROSIN IS INSTRUMENT-SPECIFIC
As you'll learn, not all rosin is created equally. Rosin is formulated and manufactured for specific instruments. Applying bass rosin on a bow you plan to use on your violin is not a good idea. When shopping for rosin, purchase rosin made exclusively for your instrument. If you play more than one instrument, purchase multiple rosins, keeping instrument-specific options in their relevant instrument case so they aren't mixed up.
PAY ATTENTION TO STRING MANUFACTURERS' RECOMMENDATIONS
Similarly, different strings work better with different rosin formulas. As you know, strings come in three variations - gut core, synthetic core, and steel core. These varying materials respond differently to changes in rosin types. Most string manufacturers recommend specific rosin types that work best with their product. Yes, some of these recommendations are made due to company partnerships or promotions but, for the most part, recommendations are sincere, and strings perform best when you use the rosin best suited to their makeup.
There are a seemingly infinite array of rosin formulations, and some are more natural than others. The fine rosin dust can get into your lungs and may also cause contact dermatitis (skin allergies) depending on your body's sensitivity. We recommend using rosin products that are all-natural to minimize exposure to harsh chemicals or other potential irritants. There are even hypoallergenic options available if you sneeze, itch, or water when exposed to rosin dust.
Read, Choosing a Rosin That's Good For You..., to learn more.
LIGHT VS. AMBER VS. DARK ROSIN
You may notice there are options with regards to dark, amber, and light rosin. Darker rosins are softer and stickier, while lighter rosins are harder and less sticky. While it's worth trying different types to create different sound quality throughout your musical career, climate should also play a role in the decision making.
For example, 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.
USE ROSIN IN RELATIONSHIP TO YOUR PLAYING STYLE
While all musicians learn - and strive to embody - "best technique practices," each musician has their playing style, and playing style may determine which rosin is best for you. Thus, a stickier rosin will be overkill for someone with a heavier hand, exerting more pressure between bow and strings. Then, those with a lighter touch and who have a difficult time exerting optimal pressure will find a darker rosin helps to bridge that by providing some extra friction.
It's worth experimenting with different rosins, respecting recommendations from strings manufacturers and your teacher(s).
PAY ATTENTION TO METAL AND OTHER ADDITIVES
Some rosins include metals and other additives said to provide different sound effects. Gold, silver, lead-silver and copper are common additions. Gold is said to provide warm, clear tones for all instruments, lead-silver is most often used by violists and violinists, and silver is considered to produce brighter tones. Copper is recommended for younger players because it's the most defined of the other additives.
BOXED OR CAKED
Typically, boxed rosin is cheaper than caked forms and easier to manipulate, which is why it's recommended for students - particularly those with non-horsehair bows. Caked rosin is higher-quality and more pure in composition.
Speak with teachers, music store professionals, and other musicians - then experiment - to find the best rosin for your instrument.