Leat Retaining Wall at Treforest Tinplate Works

Cadw's description

Location

Parallel with and detached from the W side of the former rolling mill.

History

The Treforest Tinplate Works was established in the late eighteenth century, but the surviving works dates from its rebuilding in 1834-5 by William Crawshay II of the Cyfarthfa Iron Co, although it was managed by his son Francis Crawshay. It coincided with the beginning of the accelerated growth of the British tinplate industry that continued throughout the remainder of the C19. Production began in 1836 and by 1842 it had fineries for converting pig to wrought iron, 2 mills for rolling the iron into sheets, furnaces for reheating and annealing the iron, and 2 tin furnaces in which the plates were immersed in a bath of molten tin. Power was provided by 8 waterwheels instead of steam power. The continued use of waterwheels in the age of steam was characteristic of the Cyfarthfa Iron Co and was made possible by the unusual reliability of the water supply in Glamorgan. The Tithe map of 1846 shows that the works was at that time all housed within what later became known as the rolling mill. A separate detached block to its N was probably the foundry mentioned in an inventory of 1842, but was probably demolished in the subsequent expansion of the works.

The works was considerably expanded c1854, again representative of the growth of tinplate manufacture in S Wales in the 1850s. Most of the buildings on the site, including the tin house and smithy, belong to this date, and all are shown on the 1875 Ordnance Survey. In 1876 the works was described as having 5 mills, in 1893 10 mills, while the extant tin house was designed for 12 furnaces, superseding the 2 listed in 1842. In 1896 the works was leased to Waterhouse Brothers of Bradford, but output declined in the C20. Its final owner was Richard Thomas & Co. Production ceased in 1939 when the works had 4 working mills. In 1941 the works was requisitioned for storage by the Ministry of Supply. In 1946, if not earlier, the machinery was removed and 2 large blocks N and E of the rolling mill were demolished under the Tinplate Redundancy Scheme. The site was then sold to the South Wales and Monmouthshire Trading Estate.

The manufacturing of tinplate required iron bars to be rolled into thin sheets, which were then trimmed, cleaned in an acid bath (known as pickling), annealed, re-rolled to create a smooth surface, and again cleaned and annealed before being dipped in molten tin. The sheets were subsequently polished in bran and boxed ready for dispatch. From the 1850s the sheets were rolled in the surviving rolling mill, and were then pickled, annealed and re-rolled in ranges to the E and N that have now been demolished. Tinning, polishing and packing were undertaken in the surviving tin house. Further ranges to the N and E were workshops used for various maintenance activities.

The feeder is dated 1835.

Exterior

The leat detached from the W side of the rolling mill is a retaining wall of snecked rubble, heightened or repaired with hammer-dressed snecked stone and with rock-faced copings. Opposite one of the large doorways in the rolling mill is a tablet engraved 'WC 1835 Perseverance', the latter being the Crawshay family motto. The feeder incorporates 7 sluices with cast iron frames in which the sluice gates were raised, all of which are now bricked up.

Reason for designation

The surviving buildings at the Treforest Tinplate Works constitute the most complete group of buildings in the industrial style developed in the iron and related trades of S Wales from the early C19. They form one of the most complete groups of tinplate works buildings of the C19, an industry of national importance dominated by S Wales. The leat is of additional industrial archaeological interest as evidence of the continued importance of water power in heavy industry during the C19. Listed II* for group value only.