While James P. Allaire's primary purpose in purchasing the Howell Works property in 1822 was to provide a source of raw materials for his marine engine business in Manhattan, by the 1830's pig iron production was so great he began expanding into molding and casting of machine parts, hollow ware and other marketable items. Iron casting and molding, itself, is a millennia old art which reached an advanced state of perfection by the 19th Century.
At the Howell Works Company this ancient art was begun in two separate shops: the Casting Shed and Blast Furnace Complex and the Carpenter Shop.
At the Carpenter Shop the first phase of production was begun. It was here that the wooden patterns used by the molders were hand crafted along with wooden flasks of every size. The wooden flasks had two basic parts consisting of two interlocking open ended boxes called a cope and a drag.
The molders would set the drag, or bottom box, onto a ramming board beginning the process of producing the sand mould. The pattern was placed onto the ramming board. A second pattern to form a runner was placed next to the pattern for the item being cast and both were lightly dusted with parting powder to ensure they would easily separate from the sand. The runner provided a sluiceway in the mould whereby the liquid iron could flow into the mould. The sand, a mixture of fine, sharp sand, water and clay, was mixed into a moldable composite which had adequate strength to retain its shape when the pattern was removed after ramming. Enough sand was sifted through a device called a riddle to ensure covering the pattern with a coating of clean, fine sand.
After the pattern was covered, more sand was shoveled into the drag and firmly tamped into place using a rammer. The rammer is a two sided wooden device with a handle carved in the middle. One side has an angled edge forming a sort of triangle and the other a rounded one for firm tamping. As the sand is shoveled into the drag the angled side of the rammer is used to tamp the sand into the corners and along the side of the box while the rounded side is used to firmly pack the sand in the middle. Once the drag is completely filled it is leveled off using a flat surface. The ramming board is then rubbed into place on top of the drag and the assembly is carefully flipped over. After this the bottom board is removed and small holes are made in the sand to allow the gasses to escape.
Next the, with the patterns now exposed, another light coating of parting powder is dusted over the sand mould and the cope is placed on top of the drag very carefully so as not to disturb the pattern. Sand is riddled onto the pattern. The same processes of shoveling and tamping, used for filling the drag as are used to fill the cope. Once the cope is filled with firmly packed sand and leveled off, the two parts of the flask are separated. This next is the crucial step.
Two holes are carved into the sand filling the cope: the riser and the sprue. The sprue is used to pour he liquid iron into the cavity in the sand mould The riser acts as a reservoir which feeds more of the liquid metal into the mould as the metal solidifies and contracts. A pouring basin is cut at the top of the sprue into which molten metal is poured during casting. The second part of the crucial process involves carefully removing the pattern form the sand mould. If, in this processes, the sand is disturbed the entire mould making process must be started over.
The second phase, producing the molten iron was conducted at the Casting Shed. The charge, which consisted of wheelbarrows of bog iron ore, charcoal for fuel and seashells for flux were dumped from the bridge into an opening at the top of the furnace. The heat and the gasses from the burning charcoal reduced the iron oxide to produce molten iron. The shells melted to form a flux that combined with impurities, making them more fluid and removing them from the iron. A large water wheel pumped a gigantic bellow that blew air into the base of the furnace providing the oxygen necessary to fuel the fire and also draw the carbon out of the iron. Twice a day, at twelve hour intervals, the furnace was tapped and the molten iron flowed from the tap into trenches dug into the sand floor of the Casting Shed to produce pigs, or into crucibles to be carried to the waiting sand moulds. A second tap flowed from the side of the furnace, slightly higher up from the iron tap, where the waste by-products or slag, was allowed to escape and subsequently discarded.
During this entire time the pigs, so called because in ancient agrarian societies most people thought the casting of these ingots resembled a farrow suckling at their mother, is refined in a cupola. A cupola is a smaller version of a blast furnace with one exception, the blast of air is blow in at the very base of the furnace and circulates in and around the base, preheating the air in the furnace and thereby causing a chemical reaction with the carbon in the iron. Once the iron has been refined in the cupola the last and most dangerous process begins. Cupolas were a very new concept during the time the Howell Works was in operation.
The molten iron, at temperatures of over 2200 degrees Fahrenheit, was poured from a crucible into the pouring basin. The iron travels from the basin through the sprue into the runner and hence into the pattern cavity. As cavity fills, the excess metal fills the riser. As the iron in the cavity contracts during solidification, the riser serves to provide a constant flow into the cavity guaranteeing a sound casting.
After the mould has cooled, the casting is turned out by dumping the flasks onto the floor. The sand is wiped away from the casting and picked up from the turning out board or dumping board and used again. The casting is then thoroughly cleaned off and any excess iron, including that forming the runner, riser and feeder is cut off and recycled for use again as well. The casting is then sent to the finishing department where excess iron is removed and undesirable roughness is smoothed. If desired, the casting may then be polished using a soft stone and given a finish, in many cases by heating it up and quenching it in a tank of linseed or sulfur oil to prevent rust and give a more refined look.
While James P. Allaire's primary purpose in purchasing the Howell Works property in 1822 was to provide a source of raw materials for his marine engine business in Manhattan, by the 1830's pig iron production was so great he began expanding into molding and casting of machine parts, hollow ware and other marketable items. Iron casting and molding, itself, is a millennia old art which reached an advanced state of perfection by the 19th Century.
The molders would set the drag, or bottom box, onto a ramming board beginning the process of producing the sand mould. The pattern was placed onto the ramming board. A second pattern to form a runner was placed next to the pattern for the item being cast and both were lightly dusted with parting powder to ensure they would easily separate from the sand. The runner provided a sluiceway in the mould whereby the liquid iron could flow into the mould. The sand, a mixture of fine, sharp sand, water and clay, was mixed into a moldable composite which had adequate strength to retain its shape when the pattern was removed after ramming. Enough sand was sifted through a device called a riddle to ensure covering the pattern with a coating of clean, fine sand. 
Next the, with the patterns now exposed, another light coating of parting powder is dusted over the sand mould and the cope is placed on top of the drag very carefully so as not to disturb the pattern. Sand is riddled onto the pattern. The same processes of shoveling and tamping, used for filling the drag as are used to fill the cope. Once the cope is filled with firmly packed sand and leveled off, the two parts of the flask are separated. This next is the crucial step.
The second phase, producing the molten iron was conducted at the Casting Shed. The charge, which consisted of wheelbarrows of bog iron ore, charcoal for fuel and seashells for flux were dumped from the bridge into an opening at the top of the furnace. The heat and the gasses from the burning charcoal reduced the iron oxide to produce molten iron. The shells melted to form a flux that combined with impurities, making them more fluid and removing them from the iron. A large water wheel pumped a gigantic bellow that blew air into the base of the furnace providing the oxygen necessary to fuel the fire and also draw the carbon out of the iron. Twice a day, at twelve hour intervals, the furnace was tapped and the molten iron flowed from the tap into trenches dug into the sand floor of the Casting Shed to produce pigs, or into crucibles to be carried to the waiting sand moulds. A second tap flowed from the side of the furnace, slightly higher up from the iron tap, where the waste by-products or slag, was allowed to escape and subsequently discarded.
The molten iron, at temperatures of over 2200 degrees Fahrenheit, was poured from a crucible into the pouring basin. The iron travels from the basin through the sprue into the runner and hence into the pattern cavity. As cavity fills, the excess metal fills the riser. As the iron in the cavity contracts during solidification, the riser serves to provide a constant flow into the cavity guaranteeing a sound casting.