JAIC 1987, Volume 26, Number 2, Article 5 (pp. 121 to 129)
JAIC online
Journal of the American Institute for Conservation
JAIC 1987, Volume 26, Number 2, Article 5 (pp. 121 to 129)


Ann Cordy Deegan


Cowles's process was patented in 1864.2 The U.S. Army used this patent for moth, water, and mildewproofing of wool garments and cotton tents. The ingredients are listed in Table 1 and will be discussed by their end-use role.3 Claims of ingredient roles were from historical documents (patent papers and other statements of the patent holders) and not from modern laboratory confirmation testing.


Waterproofing of fibers was stated as accomplished through use of gelatine and/or glue (later albumen). Acetate of lead and/or gum-arabic appear to have been optional but also involved in waterproofing.4 The lead acetate and gum-arabic may have been omitted by 1871.5

Blue vitriol (copper sulfate) was claimed to protect against mildew.6 Alterations to the basic recipe (1871) included substituting chloride of zinc or bichloride of mercury for copper sulfate or using a combination of the three.7

The exact ingredients for mothproofing were not specified in the 1864 patent since this patent was originally listed for mildew and waterproofing. However, Cowles approached the U.S. Army for use of the patent as a mothproofing treatment as early as 1869.8 Cowles never specified the exact ingredients used for mothproofing.

Auxiliary ingredients included alum and soap or olive oil. Alum was stated to perform as a mordant.9 Alum has been used as a mordant for natural dyes (as has copper sulfate). Soap or oil (olive oil soap) probably solubilized the alum and kept the fabric pliable.10

Water was the solvent for this process (133–158 pounds per vat) but the patent neglected to state the amount of fabric and/or garments used in each vat: the total amount of ingredients on weight of fabric is missing.11 The percentage of each ingredient by weight in the vat is given in Table 1 for both the patent of 1864 and an 1871 updated recipe. Vat preparation was very straightforward. Most ingredients were first dissolved in warm or hot water and then added sequentially.12

Toxicity of these ingredients can relate to exposure during application of the process or in handling or wearing treated items. The Quartermaster's Department made inquiries that revealed no lead in the solutions and no toxic effects to long-term employees of Cowles's plant in Philadelphia.13 These employees applied the treatment by wading with bare legs in solution vats.14 Whether there would be bias by Cowles employees from fear of losing their jobs is difficult to say.

At least one field officer questioned the possible toxicity of Cowles's-treated garments when worn by the soldiers.15 Only one officer reported anything approaching a health problem: “those who alter or repair this clothing [Cowles's-treated] complain that it is poisonous in handling and causes a burning sensation in the fingers.”16 This comment was never addressed in any of the inquiries or other documents.

Copyright 1987 American Institute of Historic and Artistic Works