We have recently finished excavating a former bleach and dye works site in Salford, Greater Manchester in cooperation with Lovell who will be redeveloping the site for residential purposes. Historic mapping showed us that by 1819 there were buildings on the site belonging to the Poplar Grove Bleach and Dye Works. The complex of buildings at the southern end of the site was accompanied by three reservoirs in the northern part, which would have supplied the factory with clean water for the bleaching and dyeing process. After we completed an initial phase of trial trenching across the site to evaluate the nature and date of any surviving archaeological remains we decided, in consultation with the Greater Manchester Archaeological Advisory Service and Lovell, to undertake an open area excavation focusing on the works buildings in the southern part of the site.
During the excavation we uncovered almost the full footprint of the former factory which has provided an interesting insight into adaptation of the buildings throughout their life as new technologies were introduced. Whilst the footprint of the buildings appears to have remained largely unchanged, evidenced by the early 19th century walls present throughout the buildings, there were additions and adaptations at various points in their life. The works can be split into two parts: an eastern range of buildings and a western range, separated by a yard or road. The eastern range was devoted to the dyeing process (as evidenced by dye residues on the floors) and the western range to the bleaching process (evidenced by the presence of lime deposits). Within the dye shop we found a dynamo, made by the Lancashire Dynamo and Motor Company in either 1912 or 1913, which represents the early introduction of electricity to the building. In the western range, the bleach croft, we encountered a series of cellars, including three beds for Lancashire boilers and an adjacent steam engine bed. Interestingly these boiler beds and steam engine rooms had gone out of use and been backfilled and built over towards the end of the 19th century or beginning of the 20th century, which again suggests a shift in the technologies employed in the process. The works remained in use up until the mid-20th century. Finds from the excavations have been relatively scarce although they include a 1920 penny from the yard, numerous milk, brown sauce and ginger beer bottles from the various buildings and a 19th century clay pipe bowl with a moulded love heart on the side. In addition there were numerous pot-eyes (used for feeding ropes of sewn together cloth through the various stages of the bleaching and dying process) and several iron cogs, crown wheels and other pieces of metal machinery.
Bleaching and dyeing was an important industry in Salford, linking in with the finishing of textiles produced in neighbouring Manchester. Raw cloth is bleached to whiten it before it is dyed and printed. In the pre-industrial period cloth would be bleached in the open air by laying the cloth out in fields (or crofts) for several months. By the early 19th century, thanks to significant developments made in powering heavy machinery and also to the invention of bleaching powder (slaked lime impregnated with chlorine gas) which sped up the process, bleaching began to be undertaken in factories. Factory based bleaching was a multi-phase process requiring repeated boiling, chemical treatments and drying before the cloth was ready to be dyed. Up until the mid-19th century dyes were obtained from natural sources, usually plants, which were then fixed into the cloth using a mordant (usually alum). In 1856 the first synthetic dye, aniline purple, was accidentally discovered and from then on new chemical dyes were produced allowing an expansion in the colours available.