During WWII, Mr. Garner became a Molder-Core maker and the parts he made went to the front lines of Europe.

From 1945 through 1953, Leonard Garner began his heat-treating experience with Roger Dexter Heat Treat and Industrial Heat Treat, expanding his knowledge of the industry.

In 1953, he was promoted and went to work with Moore Dry Dock Shipyard as Superintendent of Heat Operations, developing many heat-treating procedures. He was privileged to heat treat motor mounts for the experimental X-15 rocket that test pilot Chuck Yeager first flew, manufacture drive shafts for atomic submarines (12" diameter by 60' long), and many other parts for naval vessels.

On July 11, 1960, Mr. and Mrs. Leonard Garner began Garner Heat Treat, Inc. in a 3-car garage. Within 60 days, due to business expansion, they built their first heat treating plant in Oakland, California.

Since 1960, Garner Heat Treat, Inc. has heat treated a 3-ton cannon barrel for NASA that fires a sound wave off the moon, and an 18" diameter beryllium mirror, that bounces light beams off the moon. The company has also heat treated every guidance nozzle made for the minuteman missile, as well as small parts for the moon rover.

Garner Heat Treat, Inc. has treated millions of parts for I.B.M., Singer Corp., Harley Davidson, Pizza Inn, Pacor, all the oil refineries in the area, and many many other accounts.