JAIC 1990, Volume 29, Number 2, Article 2 (pp. 117 to 131)
JAIC online
Journal of the American Institute for Conservation
JAIC 1990, Volume 29, Number 2, Article 2 (pp. 117 to 131)

CHEMICAL WATERMARKING OF PAPER

STEPHANIE WATKINS



5 CHEMICAL ANALYSIS OF THE MATERIAL

THE TECHNOLOGY of chemically watermarking paper is considered a trade secret because it is owned and leased solely by the Customark Corporation. When patenting a new process or discovery, companies often protect themselves by listing multiple formulas and a variety of possible materials in a range of different combinations. Therefore, it is impossible to determine with certainty directly from the patents the components and proportions necessary for the chemical watermarking process.

An attempt to determine the chemical content of the watermarks in the three samples was made by performing analytical tests. The United States patents (Vaurio 1963, 1964; Skofronick and Vaurio 1966; Skofronick 1969) cite hexamethoxy methylmelamine, melamine formaldehyde, diethyleneglycol monomethyl ether (Carbitol), and epoxy as the possible primary components of a chemical watermark. Based on the repetitions of chemicals cited in the patents, tests to detect epoxy resins, formaldehyde, melamine, or urea- or melamine-formaldehyde were chosen (Browning 1977).3 These tests were destructive and should not be considered part of regular identification and examination procedures.

The test for the detection of formaldehyde yielded a positive indication of acetaldehyde in all three samples. Other tests to identify the chemical components of the watermark were negative. However, the results do not necessarily mean that the materials for which tests were chosen are not used in chemical watermarks. Different samples or more sensitive test methods might reveal more information about the resins used.

In an effort to obtain information about any possible surface treatments or paper components that might affect the results of later experimentation, standard tests for groundwood pulp, starch, gelatin, and alum were also run (Browning 1977).4 The papers did not contain lignin as indicated by tests with phloroglucinol. The tests for alum and starch were positive, indicating the presence of both. The test for gelatin did not indicate the presence of proteins.


Copyright 1990 American Institute for Conservation of Historic and Artistic Works