Kremer Pigmente GmbH & Co. KG Kremer Pigments Inc., USA37080 Acaroid, gum accroides, botany bay gum, black boy gum
Gum accroides is the resin that is obtained from Australian trees which belong to the Xanthorroeaceae species. Xanthorroea hastilis produces a yellowish resin, X. australis und X. arborea produce a reddish resin. The yellow resin is sold in large lumps, while the red resin is sold in pea-sized pieces.
Gum accroides contains various aromatic substances such as coumaric acid, cinammon acid, benzoic acid and esters of coumaric and cinnamic acids.
The resin is composed of esters of coumaric acid and cinnamic acid from the xanthoresinotannol, the yellowish colour is produced by picric acid and tannin. The resins will have a more reddish and brownish hue if more tannin is present.
The red, as well as the yellow resin are soluble in alcohol, ether and acetic acid. Solutions with alcohol, for example spririt lacquers, dry fast and make a hard drying film. These solutions are excellent substitutes for shellac and copal varnishes. Gum accroides is usually used when dark or coloured varnishes are perferred. The lightfastness of gum accroides is relatively good. In the past gum accroides was used for varnishes on metal and in the soap and leather industry.