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Accroides is a resin derived from Tate’s grass tree, Xanthorrhoea semiplana ssp. tateana, a yacca tree native to Kangaroo Island off the south coast of Australia. Several other species of Xanthorrhoea (X. australis, X. arborea, X. quadrangularis and X. preissii) which are distributed in all regions of mainland Australia produce a similar resin, which is commercially harvested and refined in the south. Lumps of resin collect naturally at the base of dead leaf stems found near the trunk of the tree. The resin is harvested during the spring season and removed by beating the stem. It is then sieved and winnowed to remove the finer foreign matter before being graded. Alternatively, a steam-operated fusion process can be used, which reduces the losses inherent in the pneumatic method.
Accroides is usually sold in the form of a reddish-brown powder known as Fine Red Accroides, or as an aggregate known as Course Red Accroides with a particle size ranging from roughly 2mm to 5mm. The resin has a balsamic, benzoin-like odour due to its benzoic acid content.
Accroides is soluble in alcohols and alkalis, and is fully compatible with cellulose nitrate and acetate, but is insoluble in water and hydrocarbons. The resin has good adhesive properties when employed as a coating, while the intense red dye has good staining power when employed in an alcoholic solution as a spirit varnish. Accroides resin is unsuitable for use in oil varnishes due to its thermosetting characteristics.
Heat-treated films have chemical resistance, as do those based on esterified Accroides. Modification with glycerin and rosin at elevated temperatures produces a composition with electrical resistance, plus proof against grease, oils and water. Several patents describe reaction with furfural and phenol, or sodium hydroxide, alcohol and p-toluene chlorosulphonate to achieve higher melting-point resins.
Accroides is used as a constituent of lacquers, varnishes, stains, sealing wax and floor polish.
Accroides is used as a constituent of shoe polish.
Accroides is used in low cost paper coatings. It is sometimes used as a substitute for Rosin in inks and paper sizing.
Accroides is used as an additive in the manufacture of paint, lacquers for metal, foil and glass, and as a base for black and brown dyes.
In the Pyrotechnics industry, Accroides is used as a source of picric acid – a raw material in explosives and ammunition, plus a binder and fuel in fireworks and flares. It is sometimes used as a substitute for Shellac but is said to have a quicker burn rate.