CALIPER
See Thickness.

CARBON PAPER
A thin tissue paper coated on one side with coloring agent or carbon black that is transferred to a sheet of paper underneath when pressure in applied.

CARBONLESS COPY PAPER
This consists of two sheets of paper. The underside of the top sheet is coated with colorless dye in minute gelatin capsules; the underneath sheet is coated with a reactive chemical that turns blue or black when mixed with the colorless dye. Pressure from a pen or typewriter on the top sheet causes the gelatin capsules to break, the dye and chemicals mix, and the blue or black copy appears on the bottom sheet.

CARTON
A container usually made of relatively thin carton or folding board, but sometimes partially or totally of plastic. The carton manufacturer delivers it to the user in either flat or collapsed form.

CARTRIDGE PAPER
Slightly rough-coated or uncoated printing surfaced paper used for a variety of graphic purposes such as envelops. The name comes from the original use for the paper, which was for forming the tube section of a shotgun shell.

CASES, CORRUGATED
Large boxes made of board that are used as containers for packages. Cases are mainly used for transit and storage purposes.

CAST-COATED
A method of drying coated paper by contact of the freshly coated surface with a highly polished, chromium-plated, heated metal surface.

CELLULOSE WADDING
A creped web or sheet of open formation made of cellulose fibers and comprising one or more plies of lightweight paper.

CHAIN LINES
Spaced lines at right angles to laid lines occurring as a watermark in paper.

CHAIN WELTS (CHAIN MARKS, ROPEMARKS)
Defect in reels due to variations in thickness across the width, resulting in the slack areas assuming a chain-like pattern around the periphery.

CHALKING
The ready removal, in the form of a powder, of an insufficiently bound layer of pigment on the paper surface resulting from the absorption into the paper of too high a proportion of the vehicle of an ink.

CHEMICAL OXYGEN DEMAND (COD)
This measures the oxygen demand caused by all impurities in the water when oxidizing a sample with a strong oxidant.

CHEMICAL PULP
See Pulp.

CHINA CLAY
A natural mineral, consisting essentially of hydrated silicate of alumina, used as a filler or as a component in a coating slip.

CHIP BOARD
An inexpensive board grade usually manufactured from the lower grades of wastepaper.

CHROMO
A term used to describe both papers and boards used for subsequent brush coating. The various qualities are determined both by the actual grade of base material used and the quality of the coating, which may be gummed. Coating may be applied to one or both sides, depending on end use.

COATED PAPER OR BOARD
Material coated on one or both sides with a mixture of china clay, latex and other loadings to fill up surface pits and improve the printing surface. The process can be accomplished either on-line on the papermaking machine or away from the papermaking machine as a separate operation. There are a variety of coating methods, these include: roll coating, blade coating, air-knife coating and brush coating, or combinations of these types. A very high-quality form of off-machine coating is cast coating.

COATING (MINERAL)
A layer of minerals applied to one or both sides of paper or board to improve brightness, gloss and printability. The mineral most often used is china clay (hydrated aluminum silicate), but calcium carbonate and titanium dioxide are also used. The coating is held together and stuck to the paper by a binder.

COCKLE
Local deformation of a sheet of paper due to unequal shrinkage giving it a slightly crumpled appearance.

COD
See Chemical Oxygen Demand.

COLLOTYPE
A planographic printing process capable of producing high-fidelity continuous tone color reproductions, i.e., no screen is used in producing the negatives from which the plates are prepared.

CONDITIONED PAPER
Paper that has been treated in the mill by exposure to hot, moist air to increase the moisture content of the paper to what is considered to be an optimum level for flatness and stability.

CONTAINER BOARDS
These boards are made to provide a variety of product containers and are made from waste materials. They may, however, be lined with bleached or unbleached kraft, or other papers, depending on end use. Some of these boards may also be treated with plastic to provide special characteristics.

CONTINUOUS STATIONERY
A grade widely used on modern high-speed accounting and similar machines. The paper is supplied in reel form and, along with the printing process, many finishing techniques can also be used, such as perforation and special folds. A particular use is for invoices, statements and similar documents, when it is normally fan-folded.

CONTINUOUS TONE
An image in which tonal gradation is produced by changes in density.

CONTRARIES
Unsuitable material found in wastepaper that must be removed from the pulp before making it into paper, e.g., paperclips, string, plastics, etc.

CONVERTER
A firm that specializes in converting reels and sheets of paper and board into packaging or finished goods for sale to the public.

COOKING
Treatment of fibrous raw material by heat in the presence of water, usually with added chemicals.

COPIER PAPER
Lightweight grade of good quality, used for copying correspondence and documents. May be glazed or unglazed. Most copier papers are laser compatible and special grades are made for color copying.

CORRUGATED FIBERBOARD
Board consisting of one or more sheets of fluted paper stuck to a flat sheet of paper or between several sheets. The following are the main classifications:
(a) Single face corrugated fiberboard. Board consisting of one sheet of fluted paper stuck to one sheet of facing.
(b) Single wall corrugated fiberboard (also known as double-faced). Board consisting of one sheet of fluted paper interposed between and stuck to two facings.
(c) Double wall corrugated fiberboard (also known as double-double-faced). Board consisting of two sheets of fluted paper interposed between and stuck to three facings.
(d) Triple wall corrugated fiberboard. Board consisting of three sheets of fluted paper interposed between and stuck to four facings.

COUCH
That section of the wet end of the paper or board machine at which the wet web leaves the vat machine cylinder or Fourdrinier wire part or other forming surface.

CREPING
Operation of crinkling paper from a roll or cylinder in order to increase its stretch and softness. This process may be carried out on or off the papermaking machine. Two types are recognized:
(a) Dry creping
An on-machine operation carried out on a dried web.
(b) Wet creping
On- or off-machine operation carried out on a wet or partially dried web.

CROSS DIRECTION
The direction in the plane of the sheet, at right angles to the machine direction, in a sheet or web of paper. The set expansion coefficient of paper is about three times as much in the cross section as in the machine direction.

CTMP
See Thermo Mechanical Pulp.

CUTTING AHEAD
Operation of slitting and cutting watermarked paper without regard to where the design falls in each sheet. The design(s) may fall in different places in successive sheets and some may be cut.

CUTTING TO REGISTER
Operation of slitting and cutting watermarked paper so that the design falls approximately in a given position in each sheet.