Casgliadau Arlein

Japan copper ingot recovered from the wreck of Earl of Abergavenny (February 1805). The ingot has a flat base forming a ‘D’ section. Has corrosion products and a marine concretion coating the surface with a pitted surface.

The term Japan copper pertained to the usual form of copper produced in Japan and traded to India. Such copper enjoyed a good reputation in India and so British copper manufacturers went to considerable trouble to duplicate both its physical form and its distinctive crimson colour (a surface layer of copper dioxide created by casting the ingots into water - J.Percy, "Metallurgy", [vol.1], London, 1861, p.394) so as to penetrate this important market. Japan copper was a commodity frequently traded by East Indiamen such as this vessel. Welsh smelters produced Japan copper from at least the mid 18th century - in 1757 Robert Morris of Swansea patented "a new invented method of fashioning and colouring copper in imitation of Japan copper" (Patent no. 711, 9 Feb 1757). By the early 19th century Welsh smelters were casting Japan copper in air rather than under water and dropping the ingots from the moulds into cold water immediately they solidified (J.Percy, "Metallurgy", [vol.1], London, 1861, pp.394-5). Mid 19th century metallurgical authors write of British production of Japan copper in the past tense, suggesting that production may have ended by the mid 19th century, the implication being that conventional western ingots of around 14 lbs weight had displaced Japan copper from the Indian market. At the time the cargo of this vessel was assembled, Welsh smelters dominated UK and international copper production, so there is a strong likelihood that these ingots were produced by Welsh smelting works. Jennifer Protheroe-Jones