Alkaline reserve
An alkaline material such as calcium carbonate or magnesium carbonate added to paper pulp during the manufacture of papers designed for archival applications to counter acidic compounds that may be in the sheet or may enter it from external sources in the future. Some compounds such as lime or calcium carbonate may have been added to historical papers during pulp preparation without realizing there were long-term pH stabilization benefits.
Abbreviation for Analytical Spectral Devices, manufacturer of the UV-Vis-NIR spectrometer used in this research.
Person in charge of operating a Hollander beater during the processing of rags and water into papermaking pulp.
Set of bars mounted in the bottom of the Hollander beater and shaped to conform to the spinning beater roll above them. In a stamper, the bedplate is the iron (or possibly bronze) surface that the stamper heads act upon when pounding rags into pulp.
Chemical symbol for the element calcium.
Chemical formula for calcium carbonate, one of the most common compounds added to paper as an alkaline reserve.
Calcium carbonate
Chemical name for CaCO3, the primary component in chalk.
Action of an enzyme or combination of chemicals and heat to break cellulose polymers apart into smaller units or their component sugars.
Abbreviation for International Commission on Illumination. See “L*a*b*,” below.
Term used to refer to the transfer of the freshly formed sheet from the hand papermaking mould to the damp felt. From the French coucher, “to lay down” or “to put to bed.”
Member of the three-person vat team who receives the mould from the vatman with its fresh sheet of paper attached and turns the mould upside down while pressing it against a damp felt, transferring the new sheet to the felt. From the French coucher; “to lay down” or “to put to bed.”
Traditional paper size, roughly fourteen by nineteen inches, or thirty-six by forty-eight centimeters.
The open wooden frame fitted to the top of the hand-papermaking mould. The deckle serves to contain the wet pulp as the vatman (or woman) shakes the mould to improve the formation quality and to cross and interlock the fibers in the sheet. From the German word deckle, or “cover.”
Delta a*
See “L*a*b*.”
Delta L*
See “L*a*b*.”
In papermaking, enzymes are proteins secreted by microbes that aid in the preparation of raw materials by breaking down unwanted components, helping to purify the cellulose fiber, and leaving the fiber more receptive to the beating step.
A process in which  pressed, damp sheets were repeatedly restacked in packs and pressed to remove excess water and smooth the paper’s surface. Sometimes paper just out of the press after gelatin sizing was also exchanged, to smooth the paper’s surface while the gelatin cooled and solidified. Sometimes termed “the exchange.”
Chemical symbol for the element iron.
A fine fiber or sheetlike projection from the surface of a cellulose fiber. Increased beating in water produces more fibrils, which are essential in the later fiber-to-fiber bonding that produces a strong finished sheet.
Process of raising fibrils from the main cellulose fiber surface.
Fibers grouped together into a small lump or nodule as a result of insufficient beating or mixing following beating.
Frost Grades
Grading system devised in collaboration with Gary Frost, University of Iowa conservator emeritus, for this research. The grades were intended to indicate the chances that there had been intervention in the natural aging of the specimens in the form of washing or resizing. The evaluation took into consideration sewing stations, degree of margin trimming, and other indicators associated with bookbinding or rebinding. Of the 1,578 specimens analyzed, 356 received a Frost grade. The results were 295 grade A (likely as original), 28 grade B (possible intervention), and 33 grade C (intervention likely). See Frost grade A “ornament” plots subset under DISCUSSION, Nonchronological Plots.
Abbreviation for grams per square meter, the weight in grams of a piece of paper if it were a full square meter in size.
Hollander beater
Dutch invention from the mid-seventeenth century designed to use windmill power and replace the heavy waterwheel-powered stampers that had been standard in the papermaking trade for at least three centuries. Rags and water were placed in an oblong tub fitted with a partition that ran along the center of its length. A beater roll fitted with bars, and looking much like a paddle wheel on a steamboat, was covered with a hood. When power was applied, the roll turned and pulled the rags beneath it, where they were caught between the bars on the roll and another set of bars mounted permanently in the bottom of the tub. The rags circulated continuously around the tub as the bar-to-bar shearing action first cut the rags into smaller pieces, then broke them up into individual threads, and finally reduced the threads to fibers. Eventually the roll was lowered to shorten the fiber and fibrillate its surfaces, softening and plasticizing it at the same time. Less beating gave a softer, weaker, and more opaque sheet, while more beating gave a harder, crisper, stronger, and less opaque sheet.
Chemical symbol for the element potassium.
The International Commission on Illumination (CIE) recommended the CIE L*a*b* or CIELAB color scale to provide a common measure for more readily comparing color values. The CIELAB color system can be visualized inside a sphere or a cube with the L* (white to black) scale running top to bottom and the a* (green to red) and b* (yellow to blue) scales running horizontally from different quadrants and intersecting each other. Because we accomplished our color measurements with an ASD UV-Vis-NIR spectrometer rather than a CIELAB standard colorimeter, we report delta L* and delta a* values but employ the same scales. Delta b* values showed no relationship with other variables and therefore are not included in the research results. For more on our color determinations, see UV-Vis-NIR Spectrometer, Color analysis under PROCEDURES, Instrumentation and Methods and Color under DISCUSSION, Nonchronological Plots.
Member of the three-person vat team who separates each sheet of pressed paper from the felt, adds it to a stack, and returns the felt to a pile ready for the coucher.
Calcium oxide, CaO. See “slaked lime” and “calcium carbonate.”
Look through
Term for the inspection of a sheet of paper when it is held up to a light source and viewed with the aid of transmitted light.
See “Materials and workmanship grades.”
Materials and workmanship grades
Ranking system of 1–5 (poor to good) devised for this research by experienced hand papermakers on our team to evaluate the quality of materials and the degree of skill apparent in the specimen analyzed. In these informed, but still subjective, evaluations, a poor quality grade of 1 was assigned if a specimen evidenced in transmitted light stray foreign fibers, straw, bits of debris, lumps, clumps, and signs of quick or unskilled sheet forming or couching. At the other extreme were grade 5 papers that appeared uniform in high-quality rag fiber content; had a minimum of stray fibers or debris; and in transmitted light showed exceptional formation quality, evidence of careful couching, and relative freedom from knots or clumps. Papers graded 2, 3, and 4 fell between these extremes. Abbreviated as “M&W grades.”
British spelling of the American word “mold,” traditionally applied to the rectangular, flat, sievelike tool used to form sheets when making paper by hand. Conveniently different from the spelling of “mold,”which all paper is susceptible to if left damp and warm for too long.
Abbreviation for “newtons per centimeter,” the units in which Pulmac zero-span and short-span test values are reported in this work.
Stack of damp paper without felts.
Percent alum on gelatin
In the paper trade the concentration of dry alum relative to dry gelatin in a sizing solution is usually described in terms of “percent alum on gelatin.” Thus if a papermaker prepares a 3% gelatin solution with alum added at “5% alum on gelatin” (mass alum / mass gelatin), then 10 liters of the size requires 300 grams of dry gelatin and 15 grams of alum. The math would be 300 × .05 = 15 or 15/300 = .05. Multiplying .05 by 100 gives the 5% figure.
Term for a transition that cellulose fiber undergoes during beating in which it becomes increasingly malleable, soft, and limp. These characteristics allow it to lie in more intimate contact with neighboring fibers during sheet forming, pressing, and drying, an effect that is, in turn, essential to good bonding and strength in the finished sheet.
The many-layered sandwich of fresh sheets of paper interleaved with felts that is built up by the coucher.
Process water
Clean and sometimes specially sourced water that comes in direct contact with the rags used in papermaking. Usually different from the main water supply used to power the mill’s waterwheel.
The fermentation of rags to subject them to enzymatic treatment that cleanses them and leaves them more receptive to beating.
Chemical symbol for the element sulfur.
Abbreviation for the “same book, different papers” subset of specimens in this research, which yielded a valuable cache of data on papers naturally aged together in the same conditions (by virtue of being bound together in the same book). To qualify for inclusion in this subset a specimen had to be one of two, and sometimes more, specimens found in significantly different condition in the same book.
A material added to a paper to change its resistance to the penetration of liquids such as oil- or water-based inks, aqueous paints, or other materials. External sizes (sometimes called “surface” or “tub” sizes), such as gelatin, or rice or wheat starch, were used during much of the history of the craft. External sizes were applied to the paper after it was pressed and dried. Internal sizes were added to the pulp before sheet forming and gave the finished, dried paper increased resistance to liquids. Rosin and alum, introduced around 1800, is a classic example of an internal size.
Slaked lime
Calcium hydroxide, Ca(OH)2. See “lime” and “calcium carbonate.”
An instrument used to gather spectra over a specific portion of the electromagnetic spectrum.
A grouping of sheets of paper, often six to eight sheets, hung together for drying.
Large mechanically driven trip-hammers or mallets fitted with metal teeth that were used to reduce rags in water to a pulp suitable for papermaking.
Stamper pit
Tub or reservoir made of wood or stone that contained the water-and-rag mixture during beating.
Papermakers term for prepared pulp. Partially beaten pulp was often called “half-stuff.”
Stuff chest
Large wooden, stone or metal container for holding quantities of beaten pulp until it was needed for sheetforming.
Term for the key pieces of hardware that act on the fiber during beating: the head nails and bedplate in the case of the stamper, the roll bars and bedplate assembly in the case of the Hollander beater.
Abbreviation used in reference to the ASD spectrometer employed in this research, which is capable of gathering spectra in the ultraviolet, visible, and/or near-infrared areas of the electromagnetic spectrum.
Abbreviation for “ultrasonic,” used in this work in connection with nondestructive testing of paper.
Paper fresh from drying, with no sizing added. Typically a waterleaf sheet is very absorbent.
Weight percent
As in “weight percent gelatin,” the term refers to the mass of gelatin over the total mass of the paper measured in the same mass units, multiplied by 100. Thus, a value of 10 on a “weight percent gelatin” plot axis in this work indicates that if the specimen tested weighed 100 grams, 10 grams of that weight would be gelatin.
Abbreviation for “X-ray fluorescence,” a technique commonly used for the detection of inorganic elements in solids or liquids.

Cite as: . "Glossary.” Paper through Time: Nondestructive Analysis of 14th- through 19th-Century Papers. The University of Iowa. Last modified . .