text: Early European bloomeries were relatively small, primarily due to the mechanical limits of human-powered bellows and the amount of force possible to apply with hand-driven sledge hammers. Those known archaeologically from the pre-Roman Iron Age tend to be in the 2 kg range, produced in low shaft furnaces. Roman-era production often used furnaces tall enough to create a natural draft effect (into the range of 200 cm tall), and increasing bloom sizes into the range of 10–15 kg. Contemporary experimenters had routinely made blooms using Northern European-derived "short-shaft" furnaces with blown air supplies in the 5–10 kg range  The use of waterwheels, spreading around the turn of the first millennium and used to power more massive bellows, allowed the bloomery to become larger and hotter, with associated trip hammers allowing the consolidation forging of the larger blooms created. Progressively larger bloomeries were constructed in the late 14th century, with a capacity of about 15 kg on average, though exceptions did exist.  European average bloom sizes quickly rose to 300 kg, where they levelled off until the demise of the bloomery.
  As a bloomerys size is increased, the iron ore is exposed to burning charcoal for a longer time. When combined with the strong air blast required to penetrate the large ore and charcoal stack, this may cause part of the iron to melt and become saturated with carbon in the process, producing unforgeable pig iron, which requires oxidation to be reduced into cast iron, steel, and iron. This pig iron was considered a waste product detracting from the largest bloomeries yield, and early blast furnaces, identical in construction, but dedicated to the production of molten iron, were not built until the 14th century.
  Bloomery type furnaces typically produced a range of iron products from very low-carbon iron to steel containing around 0.2–1.5% carbon. The master smith had to select pieces of low-carbon iron, carburize them, and pattern-weld them together to make steel sheets. Even when applied to a noncarburized bloom, this pound, fold, and weld process resulted in a more homogeneous product and removed much of the slag. The process had to be repeated up to 15 times when high-quality steel was needed, as for a sword. The alternative was to carburize the surface of a finished product. Each welding's heat oxidises some carbon, so the master smith had to make sure enough carbon was in the starting mixture.
  In England and Wales, despite the arrival of the blast furnace in the Weald in about 1491, bloomery forges, probably using waterpower for the hammer and the bellows, were operating in the West Midlands region beyond 1580. In Furness and Cumberland, they operated into the early 17th century and the last one in England (near Garstang) did not close until about 1770.
  One of the oldest-known blast furnaces in Europe has been found in Lapphyttan in Sweden, carbon-14 dated to be from the 12th century. The oldest bloomery in Sweden, also found in the same area, has been carbon-14 dated to 700 BCE.
  Bloomeries survived in Spain and southern France as Catalan forges into the mid-19th century, and in Austria as the  to 1775.