This singular name has been given to a preparation of the chestnut tree, and is employed in tanning as a substitute for oak bark and gall nuts: it is the subject of a patent granted to Charles Louis Giroud, of Queen-street, Soho, London, in 1825. The mode of preparing damajavag is as follows: The external shell of the chestnut, or the wood itself, is to be broken into small pieces, and soaked in double its weight of water for twelve hours, then boiled for three or four hours, when the liquid is to be drawn off, and filtered through a cloth or sieve to separate the fibrous matter. The liquid extract is now to be evaporated by returning it into the boiler, and the ebullition is to be renewed and continued until the extract becomes of the consistency of paste; after this it is to be cut into cakes, and dried in an oven for sale, or at once applied to the various purposes in the arts, in lieu of gall nuts. One hundred pounds of chestnut shells will thus produce about eight pounds of damajavag. The sap of the chestnut tree contains similar properties to the wood and the nut shell, but combined with a greater portion of mucilage.

The trunks of the trees may be tapped, the sap collected, and an extract made from it by simple evaporation.

Iron vessels should not be used in the preparation of damajavag, as that metal would darken the colour of the extract, owing to the affinity between iron and the gallic acid of the chestnut, their combination producing ink.