Throughout the period before the Civil War and well into the twentieth century, the methods of harvesting sugarcane in the fields remained almost unchanged. However, once the cane was cut, the process by which it was manufactured into crystallized sugar went through a dramatic transformation. The transition was from animal-powered cane mills and open sugar kettles to fully mechanized, steam-powered machinery.
Photograph of the Ashland sugarhouse
Only the wealthiest planters or those with access to very large amounts of borrowed capital could undertake sugar manufacturing with the latest equipment in the period after 1835. Kenner probably could have afforded to use the most efficient innovations, and the structural remains uncovered during archaeological excavations showed that Kenner made very rapid improvements to the sugarhouse during the initial years of its operation. However, the Ashland sugarhouse foundations indicate that Kenner failed to update the equipment with the latest technological advancements in the years just preceding the Civil War, since no evidence of newer technology was found during excavations. It is likely that between 1859 and 1862, Kenner shifted all or part of the processing of his Ashland cane to Bowden Plantation, which had newer machinery.
Cane carrier drive wheel found at the Ashland sugarhouse and simplified plan showing areas of use in the Ashland sugarhouse: A. Sugar Mill, A1. Boilers, B. Vacuum Pan, C. Purgery, D. Centrifugals, D1. Lump Room
The structural remains discovered during archaeological excavations at the sugarhouse provide evidence of the construction sequence of the building. It is likely that the sugarhouse was built during the period 1836-1839. During excavations, the original dimensions were found to be 140 ft. east/west by 45 ft. north/south. The building was modified several times over a relatively short time period. While documenting the sugarhouse these alterations were seen in areas where brick masonry patterns abruptly changed or where walls touched, but were not bonded together. At least as early as 1846, the structure was lengthened to 200 ft. to make room for a new mill for crushing the cane stalks. Thus, major alterations to the Ashland sugarhouse were made within 10 years of its original construction. Later, two long wings measuring approximately 80 ft. north/south by 39 ft. east/west were added. This expansion was necessary to keep up with the increased production capacity brought about by new technology which Kenner introduced in the early years of the plantation. Thus, archaeology shows how the sugarhouse evolved into its final, T-shaped form. A simplified plan is provided above to illustrate the layout of the building and the placement of machinery.
Typical three-roller horizontal cane mill, intermediate gearing, and engine; Schematic drawing of a cane mill engine; Mill and engine layout at the Ashland sugarhouse.
In Louisiana, the sugar harvest was a race against frost. It was important to avoid any delays in the milling and processing of the cane once the harvest had begun. After the cane was cut by the workers in the fields, it was laid on the ground in stacks. It was put in wagons or two-wheeled carts to be carried to the sugarhouse, where the cane was processed into sugar. Both two-wheeled carts and wagons were used at Ashland to carry cane from the fields directly to the sugarhouse. Kenner also was one of the first Louisiana sugar planters to use rail cars on a set of portable tracks for transporting cut cane. Light-gauge rails and metal cross-ties for a portable system were recovered next to the westernmost wall of the sugarhouse during archaeological excavations.
When the cane arrived at the sugarhouse, the stalks were thrown onto the "cane carrier." This was a kind of conveyor belt which carried the cane to the mill. A gear wheel from the cane carrier chain drive was found at the sugarhouse site in Area A (refer to plan) where the carrier was formerly located. From the cane carrier, the stalks passed through the horizontal, cylindrical rollers of the mill. This process squeezed the juice from the cane stalks the way a wringer washing-machine squeezes water from clothes. During excavation, the location of the mill was identified in Area A. The mill frame at Ashland was approximately 7 ft. wide. The top of the mill frame would have stood close to 7 ft. above the base of the frame, where it rested upon a heavy timber bed.
The large steam engine that powered the mill was also located in Area A. This was determined by using the recorded dimensions of the engine to identify the brick foundations on which it sat. The frame of the engine measured 4 ft. 6 in. in width and over 20 ft. in length. The entire apparatus probably stood an impressive 25 ft. tall.
The steam used to power the machinery was created by boilers. The typical boiler had a firebox at the end of the boiler shell or shells where wood and dried cane stalks were burned. The boiler shells contained water. The firebox heated the water in the boilers, producing steam. During excavation, the foundations for three sets of boilers and actual boiler shells were discovered. The foundations, or "boiler settings" were all located in Area A1. One of the boiler settings measured approximately 40 ft. 9 in. long and 14 ft. 3 in. wide. This provided room for 30-ft.-long boiler shells.
Vacuum pan foundation discovered during excavation, and a boiler shell found at Ashland
Drawing of a typical horizontal strike vacuum pan
After the stalks were milled, the juice from the cane ran out the bottom of the mill through a strainer into a tank. This started a number of processes generally called "clarification." During clarification, impurities were removed from the cane juice, and the liquid was thickened by evaporation. First, the cane juice in the tank below the mill was pumped into another container called the juice-heater. From the juice-heater, the warmed liquid was conveyed to a set of evaporators. Evaporators were large vessels where the heated juice was further concentrated. When the juice was thickened, the syrup was put in steam-heated vats, known as clarifiers, where impurities were eliminated by adding lime to the syrup and then straining the mixture. Clarification at Ashland took place in Area A.
The clarified, strained syrup or molasses was then placed in a closed vessel known as a vacuum pan, where it was boiled until the sugar in the syrup was crystallized. The vacuum pan operated with steam running through copper tubing inside the pan to heat the juice. During excavation, the location of the Ashland vacuum pan was identified in Area B. A number of indentations in the floor of this area showed where the cast-iron columns which supported the vacuum pan were located. Also, plates that had secured the copper tubing within the vacuum pan were found. Long brick foundations also suggested the possible location of pumps, additional engines, and other machinery associated with the vacuum pan.
The lump room of the sugarhouse during excavation
The next stage of the sugar-manufacturing process was called "purging." During purging, the crystallized sugar was cooled and then separated, as much as possible, from any remaining molasses. In contrast to milling and boiling, cooling and purging required little structurally other than the provision of adequate space.
Purging began with the removal of the crystallized sugar from the vacuum pan by releasing the crystallized sugar and molasses into hand carts or sugar wagons. The sugar was then transferred to the coolers. The coolers were long, flat troughs that were located in what was known as the "lump room" of the Ashland sugarhouse. Descriptions in the 1852 Ashland Plantation record book led to the identification of Area D1 as the lump room. After cooling, the solidified cakes of sugar were difficult to remove from the troughs. The harder the cakes became, the better the sugar they produced. Workers broke up the cakes with shovels, picks, and crowbars. The sugar was then spaded out of the cooling troughs and packed directly into large barrels, called hogsheads. The barrels had holes in one end which were plugged with pieces of sugarcane.
The filled barrels were then set on the floor over a large cistern in Area C, called the "purgery," because here the molasses was purged or removed from the sugar. The molasses remaining with the crystallized sugar would drain out of the barrels through the cane plugs into the vat. The purgery vat at Ashland was actually a mortar- or cement-covered floor sloping towards its center where the molasses would collect. Workers then filled barrels with the molasses using long-handled scoops.
Drawing of a mixer attached to centrifugals
The purgery needed to be a sizable area, since hundreds of barrels could accumulate over the course of the weeks the sugarhouse was in operation. The sugar was then shipped in the barrels, which varied in final weight from 700 to 1,200 pounds.
Before the Civil War, Duncan Kenner added centrifugals to help separate the sugar from molasses. Centrifugals spun out the molasses by centrifugal force, much like a washing machine spin cycle. Pieces of centrifugal mesh were found during excavation in and around Area D, so the centrifugals were probably once located in this area.
During sugar production, the ideal was to have the whole process working constantly, day and night, with no back-ups or bottlenecks along the way. Evidence of the hectic around-the-clock operations of the sugarhouse include the lamp wick ports and lamp glass recovered during excavations. In Louisiana, it was usual to operate the sugarhouse 24 hours a day during the harvest, stopping only when necessary to clean boilers and fireboxes. The slaves worked in shifts to keep the process going. Many planters attempted to instill in their slaves or workers a competitive spirit to pursue record sugar production with each crop. Obviously, the planter had his own interest in mind by maximizing production, although slaves may also have taken pride in the status conferred by large production. During the harvest season, the slaves enjoyed the extra food and drink supplied by some masters. Slaves might have been expected to work quickly so that the intensive workload of the harvest season would be finished sooner rather than later. A visitor to a Louisiana sugar plantation observed that the entirety of the slave force; men, women, and children, worked for 18 hours a day during the harvest season.
As one might guess, engines, mills, pumps, and other machinery, with their wheels, gearing, and leather or chain belting, combined with the feverish round-the-clock activity of sugar processing, produced a potentially hazardous workplace. Slaves, sometimes young boys, were stationed around the mill to keep the mechanism free of tangled stalks and to throw imperfectly ground cane back onto the conveyor for regrinding. It was not uncommon for the workers to be injured or killed when caught in flywheels, gears, and other moving parts.
Then too, sometimes tools would get caught in machinery and break it. It is possible that some of these "accidents" were in fact intentional resistance by the slaves and freedmen to their working conditions.
The complex machinery also demanded a skilled work force. Historical records state that the 8-to-12 hands usually at work in the sugarhouse during the 1852 sugar processing season were the plantation carpenters. While carpentry skills are not directly related to sugarhouse operations, this group of slaves was probably the largest single group of artisans on the estate. Consequently, they may have held a special status as skilled laborers. It seems that the "less skilled" work of harvesting cane was left to the field hands, while the no less taxing but more sophisticated work in the sugarhouse was performed by the artisans.
Period engraving of a typical mid-nineteenth-century Louisiana sugarhouse interior
The primary research goal of the Ashland sugarhouse excavations was collecting information on the machinery and architecture of Louisiana sugar production. This objective was successfully met. The archaeological record has substantially increased the information on where machinery was placed and the kinds of foundations needed to support them. This investigation was successful in identifying not only different use areas within the sugarhouse, but also the association of specific features with documented equipment. The excavation of the Ashland sugarhouse has been the only one of this scale in Louisiana to date. The information produced by this investigation will help future researchers understand the layout and the function of features in a typical mid-nineteenth-century Louisiana sugarhouse.