The necessity for pipe insulation was recognized after the Civil War.
January 10, 2008
Such insulation was referred to as "clothing" and usually was made of plaster, felt or even lamp-black, a fine carbon powder. These "modern" insulating materials had replaced "hair felt," a covering made from cattle hair. "It was found to have one serious defect - under the action of heat, vermin bred rapidly in this material."
From: Air Conditioning, Heating & Refrigeration News | Date: 11/12/2001 | Author: Bernard Nagengast