PULP AND PAPER DICTIONARY
This page contains definitions of the terms, words and phrase commonly used in pulp and papermaking, printing, converting and paper trading.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
RAG The term “rag” is often used interchangeably with “cotton fibre content” and harkens to a period of time when paper was actually made using cotton rags which were cleaned and then broken down into fibres which were then used to manufacture paper. In a sense it could be stated that the fine paper business has been engaged in recycling materials for production since its very beginning. Today paper is no longer made from rags and the term “rag” is falling in disfavour by the industry in lieu of the phrase “cotton fibre content”.
RAG PAPER Today rag paper is mostly made from vegetable fibres consisting of cellulose, such as cotton, linen, hemp and ramie. Rags are the most precious raw material for the papermaker. Rag papers and rag-containing papers with admixtures of chemical pulp are used for banknotes, deeds, documents, books of account, maps and copperplate engravings and as elegant writing papers. They are also used for special technical applications.
RAG PULP Papermaking pulp made from textile waste, cotton, hemp or flax.
RAGGER ROPE A rope used to remove contraries from the pulper.
RANDOM REGISTRATIONEMBOSSING / LAMINATING One of several ways in which two layers or plies of embossed product are brought together in a laminating nip for a general process known as double-nip embossing laminating. In random registration, also called DERL (for double embossed random lamination), the embossing elements do not engage, and do not even maintain a fixed relationship to each other betweent the two embossing rollers. An adhesive glue is applied to the tips of the raised elements of one of the two layers to be laminated while it is still in contact with its embossing roller. Since registration is random, many of these elements will not come into good contact with the opposing layer, and the glue will be wasted. Additional pressure in the marrying nip or shoe will be required for a good bond. Other versions of embossing laminating are nested , and pin-to-pin.
RATTLE That combination of properties such as stiffness, density etc. which is responsible for noise when the sheet is shaken or flexed.
REAM 500 Sheets of paper.
REAM - A quantity of paper, measured by area. For fine papers (not intended to be absorbent), one ream is usually 500 sheets. For absorbent tissue papers, one ream can equal 2880 square feet or 3000 square feet, depending upon the company.
RECOVERED PAPER Paper recovered for recycling into new paper products. Recovered paper can be collected from industrial sources (scraps, transport packaging, unsold newspapers...) or from household collections (old newspapers and magazines, household packaging).
RECOVERED PAPER GRADES Recovered paper sorted by types in order to be recycled by paper mills. Specific grades are used by paper mills, in order to produce different types of paper and boards.
RECOVERY BOILER Boiler used to burn black liquor from chemical pulping for recovery of inorganic chemicals as well as for energy production.
RECOVERY RATE (PAPER) Amount of paper recovered as a percentage of amount of paper consumed.
RECOVERY RATE (CHEMICAL) Amount of chemical recovered in chemical recovery process as a percentage of chemical used in pulping. Chemical loss is compensated my make up chemicals.
RECTIFIER ROLL OR HOLEY ROLL Hollow perforated roll in headbox used for even out the flow of fibres and prevent settling of fibres in headbox by providing gentle agitation.
RECYCLED FIBRE Fibre obtained from recovered paper; also secondary fibre (cf. virgin fibre).
RECYCLED FIBER PULP Pulp produced from recovered paper to be used in papermaking.
RECYCLING Use of recovered waste paper and board by paper mills to produce paper and boards.
REED General name of various perennial plants; e.g. common reed, reed canary grass, giant reed; potential feedstock for pulping and papermaking.
REEL A continuous sheet of paper wound on a core.
REFINER Equipment used to give mechanical treatment to the fibres.
REFINER MECHANICAL PULP (RMP) Mechanical pulp produced by passing wood chips between the plates of a refiner.
REFINER SAWDUST PULP Mechanical pulp produced from sawmill dust.
REFINING See Beating.
REFLECTIVITY Ability of paper or board to reflect light; a measure of gloss.
REFRACTIVENESS A measure of how much a sheet of paper deflects the light that hits it. The more light a sheet deflects, the greater its reflectivity, allowing a printed image to be more brilliant and detailed.
REGISTRATION Putting two or more images together so that they are exactly aligned and the resulting image is sharp.
REINFORCEMENT Method for strengthening paper with an insert or surface layer of glass or other synthetic fibre or metal .
REINFORCEMENT PULP Softwood chemical pulp added to give paper greater strength and to improve runnability on the paper machine or printing press.
REJECT Material removed and discarded during the cleaning and screening of pulp/stock.
RELEASE PAPER Release paper is used to prevent the sticking of glue, paste or other adhesive substances. Coating paper with silicone yields papers with a surface that prevents adhesion of most substances. Application: cover material for self-adhesive papers or films, e.g. in label production.
RELIEF A method for printing ink on paper, using type or images that rise above the surface of the printing plate. Ink sits on top of these raised surfaces, and as the paper is pressed onto them it picks up ink. Letterpress, flexography, and rubber stamps all use relief plates. In letterpress, intense pressure can cause images to be slightly debossed or depressed below the surface of the paper.
RESIDUAL FIBRES Fibres derived from sawmills scraps, plywood plants and other timber management activities.
RESILIENCE A paper's ability to return to its original form after being stretched, bent or compressed during the printing and bindery process.
RETENTION The amount of filler or other material which remain in the finished paper expressed as a percentage that added to the furnish before sheet formation. Retention can occur by various mechanisms. The simplest of these is mechanical sieving by the forming fabric. Once a fibre mat begins to form, the mat itself usually can act as a much more effective and finer sieve than the forming fabric. But even then, particles less than about 10 micrometers in size are not effectively retained by sieving. Rather, retention of fine particles requires the action of colloidal forces, including polymeric bridging or a charged patch mechanism. Retention aid chemicals can be effective either by attaching fine particles to fibre fines or fibres or by agglomerating them so that they can be sieved more effectively.
RETENTION AID Chemical additives, especially high molecular weight copolymers of acrylamide, designed to increase the retention efficiency of fine materials during paper formation.
REWINDER Equipment which slits and rewinds paper webs into smaller rolls.
RICE PAPER A common misnomer applied to lightweight Oriental papers. Rice alone cannot produce a sheet of paper. Rice or wheat straw is used occasionally mixed with other fibres in paper making. The name may be derived from the rice size (starch) once used in Japanese papermaking
RIDGES Roll defect where there are raised bands or rings of material around the circumference of the roll.
RIDGING The appearance of a series of circumferential ridges and valleys around a roll of product, where the roll appears to be corrugated like a tin can. The height and spacing of the ridges is very uniform. This is often considered a sign of poor product quality, and is usually caused by the design of the embossing pattern.
RING CRUSH TEST (RCT) A test method for measuring the edgewise crush resistance by forming the paper into a cylinder and applying a crushing force to the edge. (TAPPI T818)
RISING FILM EVAPORATOR A type of tubular heat exchanger used for concentrating a solution consisting of a non-volatile solute and a volatile solvent; solution flows upward on the heat exchange surface; vaporization ' of the volatile solvent reduces the density of the mixture and causes the vapour-liquid mixture to rise; commonly used in pulp mills but less common in new installations.
ROD COATER In rod coater, the rod is the metering device, which controls how much wet coating is allowed to leave the coating station. Typically thirty times more will be applied compared to the actual target coat weight.
ROE NUMBER Measure of the amount of chlorine required for bleaching pulp.
ROLL COATING A process in which the coating is applied by roll and subsequently smoothed by means of reverse rolls contacting the freshly coated surface.
ROOFING PAPER Board that is impregnated with tar, bitumen and/or natural asphalt.
ROSIN Rosin, a natural resin from pine trees in combination with alum, is used for internal sizing of paper in acidic paper making. The chemical formula of rosin is C19H29COOH.
ROSIN SIZE Partially or completely saponified (neutralized) rosin. The chemical formula of rosin is C19H29CONa.
ROTARY EMBOSSING Embossing by passing the material between two rotating cylinders that press the embossing pattern into the material.
ROTOGRAVURE The opposite of letterpress printing in that the design areas are recessed into the plate instead of being a relief. It is web-fed and prints thin, quick drying ink to produce multiple colours. Used in corrugated packaging.
ROUGH Heavily textured surfaces produced by minimal pressing after sheet formation.
ROUGH FINISH Paper having an exceptionally rough or coarse textured surface.
R/S Acronym for rubber-to-steel embossing.
RUBBER-TO-STEEL (R/S) Literally, embossing between two rollers where one has a steel surface that is engraved with an embossing pattern, and the other roller has a smooth rubber surface. In more recent years, this term has also been used when the engraved surface is a rigid material other than steel and/or the smooth surface is an elastic material other than rubber.
RUNNABILITY The ease with which a paper moves through a printing press or converting machine. This is primarily determined by the paper's strength, tear resistance, dimensional stability, bonding strength and water resistance
RUNNABILITY - The ability of an embossing process (or any other process) to run smoothly, without interruption, and with a minimum of attention from the machine operator or from the maintenance department.