Sproule Manufacturing Company, Inc. started manufacturing Perlite Silicate Pipe & Block Insulations in 1977 as a subcontractor to a Wilmington, Delaware firm with manufacturing rights to a Patent held by E.I. DuPont Co. The quality control of these products was so poor that breakage in shipments and handling limited its acceptance. In 1979 we requested, and were granted, a license to manufacture Perlite Silicate Pipe & Block Insulations by the DuPont Company. Our first order of business was to improve and upgrade the quality of the existing product. We developed a new formula and started producing an acceptable product with better physical and thermal properties in 1980.