Did you know?
‘Filigranology’, a word taken from the French filigrane, meaning watermark, is the study of watermarks. From the humble tracing of an image, their study has expanded to include scientific processes, such as alpha- and beta-ray photography which permits watermarks obscured by print or manuscript to be photographed. This research often provides plausible historical relationships and background information such as the date and origin of paper based, written documentation and pieces of art. There are other practical uses, and on occasions, the mill was approached to authenticate sheets of watermarked paper relating to disputed legal documents in court cases.
The thickness of a sheet of paper, or the overall density of its fibres, primarily determines how opaque the paper will appear when held to light. A watermark is a design created in the sheet of paper when the mesh of fibres has been redistributed, creating variations in the thickness and density which translate to light and dark tones.
The majority of paper manufactured today is of a wove finish, manufactured on Fourdrinier paper machines, employing dandy rolls to provide watermarks.
The most common type of watermark is created by soldering metal dies (electrotype) to the dandy roll, the name of the cylinder used on the paper machine, so they appear proud of the surface. These dies are cleverly distorted to take into account the stretching which the paper endures on the paper machine, and the shrinkage, as a result of the difference in water content of the paper between where the watermark is created, and the finished reel of paper, following pressing and drying. This method provides the very recognisable light, translucent line watermark.
An alternative type of watermark is the embossed, tonal watermark. Generally, two embossing plates are used to impart the image into the wire mesh of the dandy roll.
A cameo (relief) and intaglio (recess) embossing plate, more commonly known as male and female dies, are placed either side of the wire mesh, which has been annealed (heated). This process softens the mesh, making it more pliable and susceptible to take the design of the embossing plates, whilst preventing the individual wire strands from breaking.
Using a special industrial press, the design is imparted into the wire mesh. This process is repeated, until the whole length of the wire mesh cover which will form the dandy roll is embossed.
An example of a single tone ‘Line’ or Electrotype watermark produced at Stowford Paper Mill commemorating the mill’s bicentenary in 1987
An example of a multi-tone Embossed watermark produced at Stowford Paper Mill to showcase its watermarking capabilities