Via a trench the sugar juice from the grinder in the sugar mill ran into the sugar factory’s large boiling vessels, which were heated by burning, crushed sugar cane and leaves, later in history by coal imported to the colony’s ports. From the boiling vessel the sugar was channeled into 3-4 ever-smaller vessels to crystallize in the last tank. In the early years of the colony these pans or kettles were made of copper, but later they were made of iron. Oxholm complained that the Danish boilers were too coarse. The finer and smoother the surface of the vessels, the finer the sugar was.
A typical sugar factory was built of random rubble and various types of local stone. Squared stone blocks would shape the finer corners. Lintels above gates, doors and window arches were built of brick with strong cement made by adding the ashes of the burnt sugar leaves to the mortar. The brick building was then plastered with lime mortar made from coral limestone and sand, and finally it was whitewashed. Water was added to slaked coral lime and this was brushed on the walls both inside and outside to kill bacteria and deter vermin, and to give light to walls inside the building. The roofs were clad with wooden shingles.
Some factories were very large facilities built with ambition and prestige in mind. As a whole the generation of buildings, homes and landscape at the factory on Sion Hill was one of the most impressive, and today, although ruined, it is the best preserved of the old type of plantation building.
Since the traditional method of producing sugar was not replaced until around 1900, the ruins that are seen everywhere on St. Croix are an expression of production methods that were used from 1750 right up until 1890. In the same decade, central factories were established on plantations at Richmond, Bethlehem, Lower Love and La Grange.