Archaeological evidence of Iron Age salt-making in Britain has been largely based on the discovery of remnants of coarse pottery vessels and supporting pillars recognised as being connected with salt-making and known as briquetage. Sea water or brine from inland springs was evaporated in these vessels over fires to give a residual lump of salt.
There have been extensive finds of Iron Age briquetage in the Lincolnshire and East Anglia Fenlands and along the Essex coastline. Here the sea water was concentrated in pottery pans 60cm wide, 120cm long, and about 12mm thick. The strong brine was then evaporated in small pottery vessels supported on pillars to give the lump of salt which was obtained by breaking the vessels.
Archaeological digs at salt-making sites in Cheshire and Worcestershire have produced relatively small amounts of briquetage when compared with the coastal sites. It appears that the finished salt was distributed in the characteristic coarse pottery vessels in which it was made. The briquetage from these vessels has thus been discovered at Iron Age settlements over a wide area of Wales and western England.
Clay dug between Middlewich and Nantwich has been shown to have been used to make the pottery fragments found at these Iron Age sites. Archaeologists have also found evidence of iron-age salt-making in the area between Middlewich and Nantwich.
At Middlewich (Salinae) excavations have revealed brine kilns on which Iron Age type earthenware vessels of brine were heated.