1 INTRODUCTION

THE TECHNOLOGY of chemically watermarking paper was first patented in 1959 by Frans V. E. Vaurio for the Customark Corporation, a subsidiary of the Fox River Paper Corporation (now Company) in Appleton, Wisconsin. The Customark Corporation remains the sole patent holder for chemical watermarking of paper, though it licenses the use of the technology to other mills. Since the development of the procedure, it has been used exclusively for the watermarking of stationery letter stock and envelopes. In 1988, approximately 6.5 million sheets (13,000 reams) of paper were chemically watermarked by the Fox River Paper Company alone (Carlson 1989). Paper conservators in the near future should expect to routinely treat papers with chemical watermarks in archival collections and perhaps in modern art pieces.

“Watermarking” generally refers to a localized design, name, word, or date found in a sheet of paper. Strictly speaking, a watermark is a design. Smaller secondary names, words, and dates in the corners or opposite the main design are more accurately referred to as countermarks. However, the term “watermark” is used in this paper in the broader application, referring to the process of marking rather than to the content of the mark. The first watermarked Western paper dates from the 13th century. A cross and circle motif/design (Italy, 1282) is considered to be the first known Western example. Watermarks have not traditionally occurred in Eastern papers, although more contemporary examples exist. Watermarking originally might have been intended as an esthetic enhancement, a mark of quality, or a proprietary mark for the papermaker or the wealthy donor or client. Similar types of information, such as a particular brand of paper, manufacture from a specific mill, or depiction of a logo for a business or organization, are conveyed in watermarks today. Watermarks also relay historic information that can help date or geographically place a paper, thus validating a manuscript, document, or piece of art. The history and development of watermarks has been extensively researched. (See the bibliography for a brief listing of publications on the history, manufacture, and design of traditional watermarks.)

Watermark designs are created by sewing metal wires or soldering metal stencils onto a wire screen. In making paper by hand, the wire, known as a mold, is dipped into the wet pulp slurry is in a tub known as a vat. When the mold is removed from the vat, the excess water drains by gravity from the slurry. The fibers are distributed over the mold surface and deposited between the raised wires. In making paper by machine, the stock is run over or under the dandy roll, a wire cylinder to which the design is attached and which displaces the wet fibers in the area of design. Designs may also be impressed by localized pressure between metal or rubber rollers or dies. However the mark is produced, the result is an area in the paper that is less dense and thus more translucent when held in front of a light source. (See Further Reading for additional explanations of the variations and nuances of traditional watermarking.)

The high cost, inconvenience, and difficulty of producing intricate designs in conventionally manufactured wire or chiaroscuro1 watermarks were the impetus behind the invention of a simulated watermark in the commercial papermaking industry. The process of chemically watermarking paper allows for a greater diversity of applications at significantly lower cost. Yankoski (ca. early 1970s) cites the costs and limits a0111s being approximately $300 for a dandy roll with a minimum order of 200,000 papers (400 reams) versus $20 for a chemical watermark pattern and a minimum order of 12,000 papers (24 reams).

With the Customark chemical watermark process, unmarked paper can be made in advance and stored. When an order is received, the watermark design is produced by stamping the pre-made papers and impregnating them with the patented compound under heat and pressure. While the manufacturer considers the resulting mark to be relatively inert (Yankoski ca. early 1970s). The marks in naturally aged samples are beginning to disappear into the surrounding paper structure. This phenomenon prompted interest in chemical watermarking and resulted in this investigation into some of the characteristics of modern chemical watermarks for the benefit of conservators.