Kremer Pigments Inc. NYC: Balsams

Balsams

15 January 2011

Balsams are natural emulsions of resins and essential oils (oleoresins) exuded from conifers. Called turpentines, they are traditionally used as additives to painting mediums in oil or encaustic techniques as plasticizers. They are insoluble and immiscible in water. Unlike oils, they dry by evaporation rather than oxidation, and so can remain resoluble when dry.

Many learning about these materials find the term “turpentine” confusing when applied to both the balsams and the product obtained from the distillation of the oleoresins. Spirits (or “oil”) of terpentine are mixtures called terpenes. Balsams are made of approximately 80% of resin acids and just 20% of these terpenes.

Larch Turpentine (product 62000) is a highly viscous balsam, still sometimes called “Venice turpentine”. It is unique in that it is collected from the heart of the larch tree rather than the bark and is free from the abietic acid crystals which can discolor other turpentines. Recommended by Doerner as a non yellowing painting medium (used sparingly) to impart enamel like gloss. Used historically in making varnishes, though not recommended as a finishing varnish.Thickens further during storage.

Venetian Turpentine (product 62010) is a mixture of larch turpentine and colophony rosin, which imparts a hardness to the dried film.

Strasbourg Turpentine (product 62040) is obtained from the silver fir and named after the trading center in Vosges. The Italians called it “Trementina di Strasburgo” or “di Alsazia”. It is a less viscous balsam used historically as a varnish (dissolved in oil of turpentine) to provide special protection to easily decomposed pigments such as Verdigris. It was used also as an ingredient in oil varnishes, sometimes to dissolve more insoluble resins such as amber.

Copaiba Balsam (product 62100) comes from South American tree Copaifera landsdorfii. It is highly viscous, with a characteristic fruity odor (it has a high content of essential oil). It is also mentioned in some late 18th-early 19th century texts as a medium to protect Verdigris from darkening or changing color in oil, as well as in recipes to prepare a paint vehicle for Asphaltum. Doerner mentions its use by restorers, notably in the “Pettenkofer Treatment” for dried-out, brittle paint films to increase their refractive index and improve their appearance. (The sticky film can, however, collect dust, and the varnish would remain susceptible to solvents).

Canada Balsam (product 62110) is obtained from Canada balsam fir Abies balsamea. Highly viscous, it is unique in its transparency, pale yellow color, and high refractive index.