Shagreen leather (not to be confused with the shark or ray skin variety) was mainly made from horse or onager skin. Only a small part of the animals' backs is truly suitable.
After an initial treatment the grain side is showered with Chenopodium album (named alabuta) seeds, and covered with one or two layers of felt. This must be put under great pressure, so that the seeds leave their typical pattern in the still moist skin.
As several 19th century manuals (Hebert, 1838/Aikin, 1808) state: 'The beautiful green dye is given by soaking the inner or flesh side of the skin with a saturated solution of sal ammoniac, strewing it over with copper fillings, rolling it up with the flesh side inwards, and pressing each skin with considerable weight, for about 24 hours, in which time the sal-ammoniac dissolves enough of the copper to penetrate the skin with an agreeable see-green colour: this is repeated a second time, to give the colour more body. Blue shagreen is dyed with indigo, dissolved in an impure soda, by means of lime and honey. Black shagreen is dyed with galls and vitriol.'