The Union foundry was established in the mid-nineteenth-century to produce both iron and brass castings, likely in connection with the docks or nearby engine works. It was situated on the south-west bank of the reservoir west of the Bute East Dock (NPRN34242) and north of the Junction Dry Dock. It was expanded in the early twentieth century and later demolished.

(Sources: First, Second, and Fourth edn 25? O.S. Maps)
A.N. Coward, RCAHMW, 06.08.2018