Gamboge

Gamboge (also Gamboge, gamboge, Gutti, lat gummiresina guttae, trivial Yellow Emperor ) refers to a gum resin obtained therefrom and dark mustard yellow pigment in plants.

Origin

The traded goods in Europe historically came from Siam and Cambodia, from where it was shipped via Singapore or Canton in China to Europe. The name Gamboge (English Gambodge ), and it Gummigut, perhaps derived from Camboja, Cambodia or malay getah " latex ".

Extraction

The dye is obtained from the milky sap of the native to Cambodia, Mysore, Ceylon and Borneo species of trees of the genus Garcinia ( Garcinia hanburyi, Garcinia morella ).

For this purpose, in the cortex at least 10 years old trees spiral incisions are made, or are leaves and shoots canceled. The emerging yellow milky sap is collected in bamboo tubes. After breakage of the tubes obtained the frozen juice in the form of brown rods ( " Stangengutta "); darker, less valuable goods came in the form of lumps on the market ( " Kuchengutta ").

Properties

The crude resin consists of about 70-80 % from 20-30% dye and rubber.

Gamboge is partially soluble in alcohol, oil and water, with only the rubber portion or only the dye portion dissipates. Of the pure dye can be obtained by dissolving the resin in a lot of water and subsequent drying. It has a dark mustard yellow, transparent color. The soluble fraction is mainly composed of β - and α - Guttilacton Gambogasäure.

Use

In the Middle Ages it was in the book painting, used as application means the gilding and as a pigment for a substitute for gold ( gold varnish ). Today, it is rarely used. One field of application is the use as a pigment in the creation of violin varnishes.

To a lesser extent Gamboge came as a strong laxative used. In case of overdose, it is toxic, so it is only used in veterinary medicine.