Surviving ranges of the former Pontardawe tinplate works, which were founded in 1843 as the Primrose Forge and Tinplate Works by William Parsons, and sold to William Gilbertson in 1860s. The present buildings probably date to the later 19th century. The Ynysderw works closed in 1962. The tinplate process involved hot-rolling squares of iron sheet (blackplates), acid pickling, reheating to anneal, cold-rolling the squares to burnish (whiteplates), annealing and pickling again, before dipping in molten tin (tinning), followed by polishing, sorting and packing. The two-storey range here has the characteristic numerous flues of a tinning house, the second range has a long platform for loading or unloading in front.

Remains of the former Ynysderw works, comprising of two ranges constructed of whitewashed rubble stone with brick dressings, and asbestos sheet roofs. Both are broad. The right hand building is 2-storey, with the flues of the former tinning bays in the thickness of the wall between the seven upper windows which are widely spaced. The ground floor has various blocked openings including arches. The flues in wall are brick, and of an inverted Y-shape, so that each chimney served 2 tinning bays.
The other range is attached at an obtuse angle, and is presumably added. This is a long, single-storey range of 20 bays, lit by large windows with brick, cambered-headed, surrounds, and 20-pane iron glazing. These windows were placed in three groups of six, with large doors between. The left door of these has been blocked, and the right one enlarged. The left window of the middle group of 6 has been altered to form a door. There is a continuous raised platform along the front, and three large metal ventilators on the roof. The left end wall is rendered, with a large opening to the left.

Most of the site has now been cleared except for one large late 19th century building still in industrial use. It is one of the very few structures to retain its tinning bays and a floor of cast-iron slabs.
(Source; Cadw listing database) S Fielding RCAHMW 08/11/2006