Oil of guaiac is a fragrance ingredient used in soap and perfumery. Despite its name it does not come from the Guaiacum tree, but from the palo santo tree (Bulnesia sarmientoi).[1]
Oil of guaiac is produced through steam distillation of a mixture of wood and sawdust from palo santo. It is sometimes incorrectly called guaiac wood concrete. It is a yellow to greenish yellow semi-solid mass which melts around 40–50 °C. Once melted, it can be cooled back to room temperature yet remain liquid for a long time. Oil of guaiac has a soft roselike odour, similar to the odour of hybrid tea roses or violets. Because of this similarity, it has sometimes been used as an adulterant for rose oil.[2]
Oil of guaiac is primarily composed of 42–72% guaiol, bulnesol, δ-bulnesene, β-bulnesene, α-guaiene, guaioxide and β-patchoulene. It is considered non-irritating, non-sensitizing, and non-phototoxic to human skin.
Oil of guaiac was also a pre-Renaissance remedy to syphilis.