Botanical Name: Styrax Tonkynensis
Siam Benzoin is a natural gum-resin or, more correctly, a “balsamic resin”.
The resin is obtained from the small tree, Styrax Tonkinensis, a native of Indochina (Laos and Tonkin). Other species are known to yield similar gum-resins called Siam benzoin. The balsamic latex flows from wounds in the bark and outer wood where incisions are made deliberately. Benzoin is thus a pathologic product (it does not occur in healthy, unwounded trees). It is furthermore characteristic that not all of the benzoin trees will yield a latex after incisions.
The milky latex solidifies by oxidation and exposure to air and sunlight but when the benzoin is collected, it is already semi-solid, and it soon becomes hard and brittle, yellow-reddish, or orange-colored to pale brown￼. often translucent (thus different from Sumatra types of benzoin)￼￼. The name Siam is attached to this type of benzoin merely because of the fact, that the merchandise is often exported Via Siam (Thailand) in transit. Benzoin Siam comes in variable sizes of pebble-like, often tear-shaped pieces￼, hard and brittle, rarely agglutinated. The individual pieces are yellow-orange or yellowish-brown and a characteristic feature is an almost white or cream-colored fracture. The odor is pleasant, sweet balsamic with a distinct note of vanillin. When chewed Siam benzoin becomes plastic. Its taste is a romantic but somewhat acrid bitter and biting￼￼￼￼. There are several grades commercially available for Benzoin Siam. “Selected tears” or “tears No. 1” are considered superior for perfumery purposes. Lower grades of “tears” are somewhat darker, and they may have more insoluble matter. ‘Almonds” or “Amygdaloid” forms of Siam Benzoin give a very pale tincture or extract, but these grades are less aromatic than “selected tears”. The best grades of Siam Benzoin contain 95% or even more alcohol-soluble matter.
[ Perfume and Flavor Materials of Natural Origin — S. Arctander (1961) ]