Calcium silicate (calsil) insulation has been used for over 45 years for medium- to high-temperature industrial process piping, pressure vessels, storage tanks, and equipment. Calsil gained a strong reputation as the workhorse industrial insulation for oil refineries, power and chemical plants, and pulp and paper mills. In the early decades, numerous North American factories were producing it using two primary types of production: wet molding and filter pressing. Over time, as industrial plants began stripping and replacing calsil during turnaround, the material became associated with increased levels of corrosion under insulation (CUI). This historical trend caused the calsil market to decline, precipitating plant closures and the exit of nearly all manufacturers from the market. By 2002, the remaining North American calsil factories utilized the wet-molding production process. Today, the product is manufactured in accordance with ASTM C533 Standard Specification for Calcium Silicate Block and Pipe Thermal Insulation, Type 1. Although wet-molded calsil meets and exceeds all of the physical property requirements within the C533 type I material standard, filter-pressed calsil exhibits specific improved properties in terms of density, compressive and flexural strength, and abrasion resistance. This paper discusses advances in manufacturing technology and economic influences that fully address the historically cited reasons that engineers eliminated calsil insulation from specifications. The inherent high strength of filter-pressed, water-resistant calsil will support cladding and prevent crushing of insulation, helping to keep the primary weather barrier intact and the insulation dry. This passive protection method will improve system performance, process control, and worker safety, and reduce emissions and risks associated with CUI.