Q: What is Sackett Board?
A: Sackett Board can be considered as the first-generation gypsum panel. As a panel, it consisted of layers of manila paper separated by thin layers of gypsum. The inventor of the panel was Augustine Sackett, who received a U.S. patent on the product as an “Inside-Wall Covering.” The patent was filed on May 23, 1890, and issued as Patent Number 520,123 on May 22, 1894. Along with developing the panel, Sackett is credited with inventing the mechanical equipment to produce the product.
Sackett was born in Connecticut on March 24, 1841, and spent his life in the northeast portion of the United States. At the time of his death in 1914 he was residing in New York City. In 2017 he was inducted into the Inventors Hall of Fame for Sackett Board.
The paper is described in the patent as having the properties of “builders’ sheathing paper.” In between the layers of paper is a thin layer of “plaster of Paris” or calcined gypsum. The number of individual layers will depend on the final thickness of the desired panel. The panel thickness deemed necessary for “ordinary purposes” would be 3/16 of an inch. This would require a minimum of eight layers. The paper on one side could be “waterproofed” either by the composition of the paper or a coating on the paper itself. This product would then be installed on exterior walls with the waterproof side facing the stud cavity. Further, he envisioned the possibility of substituting the gypsum plaster with hydraulic cement. This was written into the patent. He also included the possibility of core additives such as sugar or molasses to enhance the hardening characteristics of the gypsum.
The manufacturing process was such that a base layer of paper, the size of the intended panel, was laid out. To this a thin layer of gypsum was applied while still in a fluid state. To the top of the plaster another layer of paper was added. The thickness of the plaster can range from “one one-hundredth to five one-hundredths of an inch.” Additional alternating layers of gypsum and paper were added until the final desired thickness was achieved. At this point the panel was placed between “flat surfaces” to which pressure was applied to produce an even plane when the plaster had set.
These panels were designed to replace conventional wood lath and plaster and thereby drastically reducing the time of construction. The patent drawings illustrate application of the panels over conventional open wood framing in either a wall or ceiling application. Installation calls for nailing the perimeter of the panels to the framing. The joints of the panels were then concealed with “wall paper.” It could also prove useful as a lathing or base material for plaster. In this capacity it efficiently replaced wood lath, and thus began the use of gypsum panels as a base for plaster.
The original patent drawings depict a few interesting items. The first is that the fastening is only around the perimeter of the panel, and no fasteners to the single framing member are shown in the field of the panel. This would indicate the panel width was 32 inches. The product is shown rectangular in shape, so the length could have been 36 inches. Documentation on the actual size varies so the length dimension is, at best, a guess. The common thickness was listed at a nominal 1/4 inch. The drawings further indicate that installation was not done in a running bond fashion, and all the panel joints were aligned. The panel edges were not wrapped in paper, which left the gypsum exposed. This would prove problematic, especially with the resulting high probability of edge damage.
The resulting product became popular and by the turn of the century the company was producing several million square feet of product a year. This caught the eye of one of the plaster manufacturers and the New York City–based Sackett Plaster Board Company, including its several plants, was sold in 1909. This led to a rapid evolution of the product where by 1916 it more closely resembled the gypsum panel of today. During 1917, the original Sackett Board ceased production.
While the production of Sackett Board spanned only approximately 25 years, it opened the way for a huge transformation in the way buildings were designed and constructed. The product also was the start of an entire new industry focused on the production, transportation, distribution and installation of gypsum panels.
Robert Grupe is AWCI’s director of technical services. Send your questions to [email protected], or call him directly at (703) 538.1611.
