Gypsum and Plaster In Utah

Plaster. The use of plaster on buildings dates back to very remote times. Evidence shows that thousands of years ago primitive man erected dwellings of sticks plastered with mud. As man advanced he discovered and employed a plaster that was more lasting and sightly than mere mud. Specimens of early plaster work show that the material used then was indeed similar to that which is now prepared scientifically. It had both the qualities of beauty and durability. On the pyramids of Egypt is found plaster work that has endured for over 4000 years, or since these great monuments were first erected. Again, the very tools which plasterers used at that remote period are similar to those still in use.

Several centuries before the birth of Christ, the Greeks used plaster of a fine quality as stucco on some of their temples. Even buildings constructed of marble were sometimes plastered, both inside and outside. A plaster made from gypsum was used for ornamental work by both Egyptians and Greeks. Down through the ages this art has continued. It reached a high stage of perfection in the day of King Henry the Eighth. Craftsmen of today admire the ornamental plaster work on walls and ceiling in the houses of that time.

Gypsum, the mineral so commonly used in plaster, is widely distributed. It exists in considerable quantities in our state, especially in the central and southern parts. Not all of it can be used. Some of it exists in crystallized form. In this form it is called selenite. Some of the largest known crystals of selenite have been found in southern Utah. The form of gypsum most desirable for commercial purposes is the massive non-crystalline variety. Large deposits of this variety are found near Nephi in Juab County and Sigurd in Sevier County. In each of these places mills have been erected and different kinds of plaster are manufactured.

The plaster plants, one of which has operated for more than forty years, employ on an average 58 people throughout the year. Salaries and wages paid amount to nearly $100,000. The product is sold both in the state, in nearby states, and in the coast states. Utah-made plaster was used on several of the fine buildings erected for the Panama-Pacific Exposition held at San Francisco. Recently the government selected the Utah product for plastering the houses erected at Boulder City, Nevada.

Gypsum. Large deposits of gypsum occur in several localities in the south-central part of Utah. Not all of these deposits are within reach of transportation facilities at the present time; some of them stand untouched as yet and will supply the needs of generations to come. About 45,000 tons of gypsum are mined yearly and this output is valued slightly less than $300,000. A large part of this product is used in the manufacture of plaster.

Gypsum is abundant in Utah and was recognized very early in pioneer history. The mineral was discovered in Salt Creek Canyon before Nephi was settled (1851). A claim, located about 1870, was patented by John Hague and others in 1882 under the name of the Juab Plaster and Mining Claim. During the next few years rock gypsum was quarried and calcined in sorghum pans, and the plaster was used locally and shipped to Salt Lake City.

A mill was built in 1888 by Hague and others. This property was later acquired and operated up to the 1930's by the Nephi Plaster and Manufacturing Company.

Four gypsum mills were operating in Utah in 1910 — one at Nephi, one at Levan (Juab County), and two at Sigurd (Sevier County). Total mine production was 46,279 tons valued at $149,089, of which, 31,333 tons were calcined for plaster, 12,301 tons were sold to cement plants, and 4,185 tons were used for land plaster. The Levan plant had closed by 1923, and during the early 1930 depression years, total gypsum production from the remaining plants dropped to 22,000 tons but rose to 58,000 tons in 1939.

Production of gypsum in Utah up to the 1940's was principally for Utah markets. Greatly increased postwar demands for prefabricated gypsum products in both local and outside markets encouraged the U.S. Gypsum Company and the Western Gypsum Company (now the Bestwall Gypsum Company) to build large, modern plants at Sigurd, Sevier County, for production of a full range of gypsum products. These plants were completed in 1947 and are now the only Utah gypsum operations. Detailed figures are not available, but present production is estimated at about 200,000 tons of wallboard, plaster, and Keene cement annually.

Situated about a mile from Nephi City, at the mouth of Salt Creek canyon, are the Nephi Plaster and Manufacturing Works. The factory proper covers about 60 by 75 feet. Annexed to this building is a cooper shop 14 by 30 feet. Here the barrels in which the plaster is shipped are made. This entire plant is operated by one hundred and twenty horse waterpower under eighty live feet head.

The largest deposit of gypsum in America is located within four hundred feet of this mill. The process of manufacturing into plaster is not intricate, though it is somewhat lengthy.

The rock is conveyed from the quarry to the mill by means of cars. It is then thrown into a large iron crusher, where it is broken into pieces not much larger than a pigeon's egg; then conveyed to another machine which grinds it to a powder.

Thus reduced it is transferred to a large iron kettle under which is a hot fire. During the boiling process, which occupies two and a half hours, it is kept in motion by a mechanical contrivance. The drying is done by a centrifugal machine. Every particle of moisture is driven out by the rapid rotary motion.

The process is now completed. The plaster is ready for packing and shipping.