Sandarac

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Sandarac (or sandarach) is a resin obtained from the small cypress-like tree Tetraclinis articulata. The tree, which may itself also be referred to as sandarac, is native to the northwest of Africa with a notable presence in the Southern Morocco part of the Atlas Mountains. The resin exudes naturally on the stems of the tree. It is also obtained by making cuts on the bark. It solidifies when exposed to the air. It is sold in the form of small solid translucent chips with a delicate yellow tinge. Morocco is the main place of origin of sandarac. A similar resin is obtained in southern Australia from some species of the Australian cypress-like trees Callitris, but the resin has not been systematically collected. Historically, especially in the Late Medieval and Renaissance era, sandarac was used to make varnish. When "varnish" was spoken of in Renaissance Italy (Italian vernice) it usually meant sandarac. Copal and other resins displaced it as equally good and less expensive varnishing materials. Nevertheless, sandarac varnish is still valued today for use as a protective coating on paintings and antiques. It gives a coat which is hard, lustrous and durable. The varnish is made by melting the resin and mixing it with (e.g.) linseed oil. Sandarac resin melts at about 150 °C to a colourless or slightly yellow liquid. Its specific gravity is about 1.04. In mid- to late-19th century photography a varnish was applied as a preservative to photographic negatives and positives. Sandarac resin was preferred by some photographers for this purpose. Although it is not very strongly aromatic, sandarac resin was and is also used as incense. The aroma has been compared to balsam.