Documenting Two Historic Sugar Mills On Kauai

The Lihue Plantation Company started one of Hawai‘i’s first sugar mills in Lihue in 1849, boiling juice into syrup in open kettles. The Kekaha Sugar Company started a mill in 1880, by which time the technology had already advanced from water-and-animal powered machinery to a complex mechanical process driven by steam power, and by 1892 railroads had replaced oxcarts in transporting cane from field to mill. After years of successful operation these two mills closed in 2000 and were scheduled for demolition. In 2008, to mitigate the loss of these historic properties, which met the criteria for inclusion in the National Register, Mason Architects prepared Historic American Engineering Record reports to document the architectural and mechanical elements of the two mills and their supporting structures.

The reports provide a general history of sugar cultivation in Hawai‘i. They explain how Hawai‘i, though not the largest, was the most efficient producer of sugar, by constantly improving fertilization, pest and disease control, irrigation, the variety of sugar planted, and by installing better machinery.

The reports also provide a detailed analysis of the sugar-making process at each mill, which developed over the 19th century and did not greatly change after the 1920s.

  • The cane must be processed within eight hours of being harvested, or it will ferment.
  • It is transported to the mill and is unloaded onto a conveyor where trash and rocks are removed and the cane is cleaned.
  • It passes through rotating knives where it is cut up, then sent to a crusher (two rollers with interlocking corrugated teeth), which extracts much of the juice from the cane, and to a shredder, which separates the cane fibers.
  • Now a uniform blanket, the cane moves to the grinding mills, where grooved rollers and rinsing the cane with hot macerating water or cane juice extract 98% of the juice.
  • At this point the remaining fibrous material, bagasse, was conveyed to the storage house until it could be used as fuel for the mill’s steam boilers; while the juice was weighed and then clarified by heating it and adding lime to precipitate sediment. The sediment was then filter-pressed to remove any remaining sugar juice, which was sent back to be clarified.
  • The clarified juice was next sent through a series of evaporators where it was heated under a vacuum to evaporate water and thicken the juice to a syrup.
  • After sitting in a holding tank, where impurities settled to the bottom and were returned to the clarifiers to be reprocessed, the syrup was heated in vacuum pans until the super-saturated solution formed sugar crystals and molasses.
  • This viscous mixture, called massecuite, was sent to crystallizers to be cooled, then sent to centrifugals to separate the sugar from the molasses.

The mills operated 24 hours a day in season, 5-2/3 days a week for 37-38 weeks out of the year. In the November-March off-season, workers made improvements and installed new equipment.

Through examination of documents in the Hawai‘i Sugar Planters’ Association archives at the University of Hawai‘i, the Kaua‘i Historical Society, newspaper articles, secondary sources, and hundreds of drawings discovered in the abandoned mills, the architectural historians have created a record of the expansion of each mill, its succession of managers, production statistics, and technological improvements over more than a century of operation.

They have also fully described in detail the buildings in each mill complex as it exists today.

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Photos: David Franzen

Boiling house, Lihue Mill.