Spanish licorice (pigment)

A fugitive brown extract obtained from the roots of the Spanish licorice plant, Glycyrrhiza glabra; it is water soluble and forms a sticky, viscous fluid. The brown liquid was used as a thin, transparent glaze for paintings; it was sometimes added to bister to improve its working properties. It is also used for other purposes, including in fire extinguishers and added to fiber-based insulated building boards as an insect repellent.