Guardian Rock Wool Plant, Easley, Mo. ca 1940

Boone County Historical Society collection. Donated by Roberta Easley Morris.

This photograph, taken about 1940, shows the first of two rock wool plants located near the community of Easley on the Missouri River in southwest Boone county. The Guardian Rock Wool company, was incorporated in the State of Missouri March 23, 1939, with $50,000 worth of capital stock. The new plant began operating in 1940. The man in the foreground is thought to be a Mr. Crane, one of the first foremen.

Boone county records show that the corporation began business with $7,500.00 in cash (or 75 shares) plus machinery and tools valued at $6,400.00 (or 64 shares), with the remaining 361 shares to stay in the treasury “to be sold if additional capital is needed.” The initial stock holders, all from Columbia, were:
M.E. Callander - 58 shares
T.B. Haffner - 10 shares
J.M. Allton - 21 shares
Lee Hillis - 10 shares
L.A. Nickell - 10 shares
D.B. Robnett - 5 shares
Frederic Dunlap - 25 shares

The first plant building caught fire within the first year or two of operation and was replaced by a second plant located a short distance away.

The production of rock wool required a highly technical process that liquified the special composition limestone quarried from the bluffs behind the plant. The liquid rock flowing from the coke furnace was shock cooled with air or steam jets resulting in a fluffy, fibrous material that was an excellent building insulator. This was the first widely available insulating material for many homes in the United States and is still produced in some facilities.