Hopewell Furnace

Hopewell Furnace National Historic Site
2 Mark Bird Lane
Elverson, PA 19520
610-582-8773

At the beginning of the 19th century, cast iron products were created using blast furnaces that were not much different from those used in China over 2,000 years ago, or in 12th century Medieval Europe.

Hopewell Furnace was built in 1771, a time when such manufacturing activity was prohibited by the Iron Act of 1750. The British intended their colonies to be sources of raw materials and markets for finished goods; not competition for their own manufacturers. Despite this ban, one-seventh of the world’s iron goods were being produced in American furnaces, forges and mills by the onset of the Revolutionary War.

The presence of abundant natural resources was a decisive factor in favor of the colonies. The process required iron ore, wood and limestone. Wood was used to create charcoal – keeping the furnace hot for one day consumed an acre of woodland. Calcium-rich limestone was used as flux; in the hot furnace calcium drew impurities from the ore, and purified molten iron sunk to the bottom.

Around the commercially successful furnace developed an “iron plantation”, which was a self-sufficient community of craftsmen, laborers and their families. At the head of the community was the ironmaster, who was often the property owner. An ironmaster needed to be a financier, technician, bill collector, market analyst, personnel director, purchasing agent, and host to prospective buyers. The second in command was the clerk, who kept books, ordered supplies, served as paymaster, and managed the office store.

Hopewell Furnaces’ peak years were 1816-1831, when the plantation was under the imaginative leadership of Clement Brooke. Later on, anthracite coal replaced charcoal as the fuel of choice in iron production. Anthracite is a much denser substance than charcoal, therefore it contains much more carbon per unit volume. Hopewell Furnace attempted to switch from charcoal to anthracite, but the coal region was in Northeastern Pennsylvania, and transportation expenses put Hopewell Furnace at a competitive disadvantage. The introduction of the Bessemer steel production process brought on the development of the American steel industry in the second half of the 1800s, further contributing to the decline of wrought iron facilities such as Hopewell Furnace, which finally went out of business in 1883.

In this photograph a moulder is demonstrating the preparations required for “flask casting” a stove plate. A flask was a pair of wooden frames – one such frame is shown here. Each frame was filled with sand, and a wooden pattern was placed flat on top of the sand. A different side of the wooden pattern was face-down in each frame. After the shape of the pattern was carefully engraved in the sand, the pattern was removed and the two frames were joined together – creating an empty cavity in the shape of the wooden pattern. Molten iron was then pored through an opening made through the broad top of one of the frames. A series of identical “flasks” was thus prepared, and molten iron brought from the adjacent furnace was emptied into the flasks, one-by-one.

The ironmaster received orders from various manufacturers. In the case of this stove plate example, each stove manufacturer supplied his own, unique wooden pattern with which moulds were created.

Iron ore, charcoal and limestone were dumped into the furnace from above, and molten iron was taken from a crucible placed at the bottom. Oxygen was supplied through an air duct visible at the bottom-center of the furnace. A water wheel powered a bellows which blasted in a constant supply of fresh air. Hence the name blast furnace.

Colliers created a stack of wood, covered it with leaves and dirt, ignited the wood and allowed it to smolder for ten days to two weeks. Covering the wood allowed oxidation to occur without the ignition of flames. Impurities slowly escaped through the covering, and carbon-rich charcoal remained below.

Colliers lived as nomads, often dwelling in primitive, cone-shaped huts. The second photograph is of a photograph on exhibit at the Hopewell Furnace site.

The ironmaster’s mansion served as the community center. That’s where visitors were entertained, meals were served to craftsmen and important occasions (such as weddings) were celebrated.

Behind the ironmaster’s residence was a spring house. A small structure was often built over a nearby spring, whose cool waters helped to preserve perishable items. The second photograph shows how goods such as meat and dairy products were stored in the springhouse cellar.