General Alum & Chemical Corporation was formed in 1979 by James A. Poure. The companys first production facility was a liquid aluminum sulfate (alum) manufacturing plant in Indianapolis, Indiana. The company was headquartered in northwest Ohio.

In 1983, a second alum production plant was built in Toledo, Ohio. Then in 1989, the third plant was built in 1989 in Saukville, Wisconsin.

The company was named one of the fastest growing, privately held companies in the United States by Inc. Magazine in 1984. Since that time, the company and its founder have been twice awarded the prestigious Ernst & Young Entrepreneur of the Year Award.

A large acquisition was made in March, 1994, when General Alum purchased the assets of Delta Chemical Corporation of Searsport, Maine, a 152 acre facility located on the coast of Maine. Various chemicals are produced at this plant site to serve our regional, national and international customer base.

In November, 1999, at the time of the 20th anniversary of the company, General Alum & Chemical changed its name to GAC Chemical Corporation. The renaming was designed to reflect the two-decade evolution from a small single location producer of one chemical to a diverse multi-producer and distributor of industrial and specialty chemicals. The new name was specifically chosen to emphasize the broadened capabilities and growth plan of the company as well as to maintain the connections with the corporate beginnings.

In May of 2003, the Toledo, Ohio; Indianapolis, Indiana; and Saukville, Wisconsin plants were sold to a venture capital group. As a result of this transaction, the corporate headquarters moved to Searsport, Maine.

James A. Poure maintained majority ownership of the corporation until June 23, 2015 when he sold his equity stake to a newly formed Employee Stock Ownership Plan. GAC Chemical Corporation has joined the ranks of other prominent Maine companies such as Cianbro, Sargent Corp. and Dennis Paper that are owned by their employees.