He is also the co-inventor of the first pre-sensitized metal lithographic printing plate. Working with John M. Case, he developed a simple, inexpensive printing plate which revolutionized the lithographic printing industry. The "Jewett & Case" plat was the first of a new generation of inexpensive metal-backed pre-sensitized lithographic plates having long press life and providing quality reproduction. Introduced in 1950, it helped speed a worldwide industry change from letterpress to offset printing, set the standard for the worldwide offset printing industry, and formed the cornerstone of 3M’s new Printing Products Division, whose 1978 dollar sales volume was in the multi-millions.
Clifford L. Jewett
(1909 - 1986) Clifford Jewett was a 3M research chemist and engineer whose inventions are in the two strikingly dissimilar fields of roofing and printing. He developed methods for artificially coloring granules used in asphalt roofing to provide improve weatherability and increase attractiveness. These ceramic-coated granules gave consumers a wider choice of colorful, longer-lasting roofs for their homes, and rapidly found commercial acceptance by the asphalt roofing industry during the 1930s. He is listed as either sole or joint inventor on seven patents. He was awarded one of the two basic patents which provide the foundation for much of today’s roofing granule technology. Many of the roofing materials sold today have colored granules with fused ceramic coatings made using methods developed by Jewett.