Rosin is made from the resin collected from a variety of trees, most often pine. If the resin is tapped from the trees between late winter and late spring, it is a golden amber colour; as the seasons progress, the natural colour of the resin darkens and this resin is more suitable for the softer rosins. Resins collected from different parts of the world also have differing characteristics in terms of colour and hardness.

There are various ways of treating the raw resin during processing. Once collected, the resin is “cleaned” which would include heating to allow water to evaporate and filtering to allow impurities, such as bark and twigs, to be removed then the resulting pure liquid resin is skimmed and cooled.

The pure resin is heated again and different oils, waxes and dyes are added. This procedure differs between manufacturers and is a carefully guarded secret. The resulting liquid rosin is poured into moulds to form the final “cake” musicians are familiar with. These differences mean that rosins can have different qualities and influences, depending upon the manufacturer’s technique and recipe. Rosins of different quality will affect bowing technique and the specific sound colour of the instrument.

In general, violinists and violists can use a dryer or harder rosin (usually a lighter colour) because their strings are generally of small diameter and are relatively light weight. Cellists have to “drive” a heavier, larger diameter string and so may prefer to use a medium or slightly more sticky (or soft) rosin. These soft rosins are easier to apply to the bow hair and this gives a firmer contact with the strings. In either case, only a thin layer of rosin is required.

Steel strings play better with dry or harder rosin, synthetic strings with medium rosin and generally gut or wound gut strings prefer a more sticky rosin.

Some players will use a harder rosin in summer when temperatures are high and revert to a softer one in winter, thereby keeping the same basic “feel” in the bow.

The Liebenzeller Metall-Kolophonium (Gold) Rosin I, II, III and IV may be of interest to some players.

According to the manufacturers, Liebenzeller Gold Rosin enhances the quality of the tone, giving greater warmth, flexibility and radiance. It increases the capacity for modulation, volume and carrying power in large halls, gives a good, even response and reduces surface noise. It is scarcely affected by variations of temperature or humidity and leaves a minimum of residual dust.

Liebenzeller Gold I is suitable for Violins
Liebenzeller Gold II is suitable for Violins and Violas
Liebenzeller Gold III is suitable for Violas and Celli
Liebenzeller Gold IV is suitable for Celli

As can be guessed, Liebenzeller Gold rosin is graded I to IV in order of hardness, with I being the hardest and IV the softest.

Examples of dry or hard rosins are:

Paganini
Hills Light
Piranito
Kaplan Art Craft Light
Etude
Liebenzeller I and II


Examples of medium or sticky rosins are:

Hills Dark
Kaplan Art Craft Dark
Obligato
Oliv
Eudoxa
Cellisto
Liebenzeller III and IV