Uncaria gambir sarawak, the gambier or gambir, is a species in the genus Uncaria found in Sarawak.
Gambier is used in Sarawak for chewing with areca and betel, for tanning, and for dyeing. It contains flavan-3-ols (catechins) which are known to have medicinal properties and are components of Chinese herbal remedies and certain modern medicines.
To make gambier, the leaves are first boiled in water. They absorb it and turn brownish in color. The leaves are then pressed mechanically to squeeze and extract liquid. This liquid is then dried into a semi-solid paste and molded into cubes, which are dried in the sun. Gambier is generally packed in 50 kilogram multilayered packing (PP Bags inside and gunny bags outside).
Diplomat Edmund Roberts noted that upon his visit to China in the 1830s, Chinese were using it for tanning, and noted that the uncaria gambir made "leather porous and rotten." He also noted that Chinese would chew it with areca nut.