C Glossary 43
surface roughness Surface roughness of papers can affect print quality, feeding, and
fusing (toner adhesion). If paper is very smooth, background particles are more easily
seen, and sheets tend to stick together and create multiple-sheet feeds. Very rough
papers can degrade transfer of toner onto the page, causing jagged edges or toner
scatter. Fusing (toner adhesion) can also be drastically reduced on very rough papers.
Roughness is usually measured using an air leak method such as the Sheffield
method. Typical Sheffield values for different paper surfaces are within the following
ranges:
• about 120 to 150 for photocopy grades (wove or regular finishes)
• about 40 to 60 for very smooth laser or coated grades
• about 250 to 300 for cockle finishes
• greater than 350 for traditional linen and laid finishes
watermark An impression made in a wet sheet of paper as it is being manufactured.
Watermarks are visible when the sheet is held up to light. They appear as a word,
symbol, or other impression.
waste paper A generic term used for post-consumer waste and some pre-consumer
waste.
wax pick Characterizes the resistance of the surface layer of a sheet to the breakaway
of surface fragments. Expressed in Dennison units.
