A machine used to rub, macerate, bruise, and cut fibrous material, usually cellulose, in water suspension to convert the raw fiber into a form suitable for formation into a web or desired characteristics on a paper machine. The many types of refiners differ in size and design features but most can be classified as either jordans or disk refiners. Beaters are not usually referred to as refiners although in a broad sense they serve a similar function.
Retention
The amount of filler or other material which remains in the finished paper expressed as a percentage of that added to the furnish before sheet formation.
Rewinder
See Winder. The term rewinder is often used for the winder in the finishing room, distinguishing it from the winder that follows the slitter at the end of the paper machine.
Sheffield
A test used to measure the smoothness of paper by measuring the rate of airflow over the surface of the sheet. The lower the number, the smoother the sheet.
Size
Any material used in the internal sizing or surface sizing of paper and paperboard. Typical sizes are rosin, glue, gelatin, starch, modified celluloses, synthetic resins, lattices, and waxes.
Sizing
(1) A property of paper resulting from an alteration of fiber surface characteristics. Internal sizing is a measure of the resistance to the penetration of water and various liquids. Surface sizing relates to the increase of such properties as water resistance, abrasion resistance, abrasiveness, creasability, finish, smoothness, surface bonding strength, and printability, and the decrease in porosity and surface fizz; (2) the addition of materials to a papermaking furnish or the application of materials to the surface of paper and board to provide resistance to liquid penetration and, in the case of surface sizing, to affect one or more of the properties listed in (1).
Smoothness
The property of a surface determined by the degree to which it is free of irregularities. In printing, the smoothness of the paper in the printing nip is important and is referred to as printing smoothness. Smoothness improves as the paper is compressed and locally deformed under mechanical pressure.
Softwood
Wood from coniferous trees whose leaves are needlelike such as pine, spruce, or hemlock or scale-like as cedar.
Softwood Pulp
A pulp made from softwood or coniferous wood species.
Speck
A particle of contrasting appearance in pulp or paper.
Starch
A white, odorless carbohydrate found in various plants. When extracted and purified, primarily from tapioca, corn, potatoes, and wheat, it is used in paper as an adhesive or sizing agent.
Stiffness
The ability to resist deformation under stress. Resistance to a force causing the specimen to bend is termed bending or flexural stiffness.
Stock
(1) Pulp which has been beaten and refined, treated with sizing, color, filler, etc. and which after dilution is ready to be formed into a sheet of paper; (2) Wet pulp of any type at any stage in the manufacturing process; (3) Paper on inventory or in storage; (4) Paper or other material to be printed, especially the paper for a particular piece of work; (5) A paper suitable for the indicated use, such as coating raw stock, milk-carton stock, tag stock, towel stock, etc.
Stock Preparation
A term for several operations that occur between pulping (or bleaching) and formation of the web on a paper machine. It may include, for example, repulping, beating, refining, cleaning, etc.
Supercalender
A calender stack used to increase density, smoothness, and gloss of paper. It is constructed on the same general principle as the calender, except that alternate chilled cast-iron and soft rolls are used in the supercalender. The soft rolls are constructed of highly compressed cotton or paper. It is not an integral part of the paper machine, whereas the calender is.
TAPPI
An acronym for the Technical Association of the Pulp and Paper Industry which is concerned with the establishment of testing standards, etc. for the pulp and paper industry.
Tearing Resistance
The force required to tear a specimen under standardized conditions. Two methods of measurement are in common use: (1) Internal tearing resistance, wherein the edge of the specimen is cut before the actual test; and (2) Edge tearing resistance.
Tensile Strength
The maximum tensile stress developed in a specimen before rupture under prescribed conditions. It is usually expressed as force per unit width of the specimen.
Titanium Dioxide
The white oxide of titanium, TiO2. There are two crystalline forms useful to the paper industry: the anatase form employed primarily as a filler pigment and the rutile form used primarily in pigmented coatings. Both types are particularly useful because of their white color, high brightness, and high refractive index (2.52-2.76) that make them highly effective for improving both brightness and opacity. Commercial grades are usually treated to facilitate use in the many papermaking and coating applications and to provide particle size for optimum optical behavior.
Tooth
Refers to a paper’s surface roughness.
Tub-Size Press
Generally a unit of a paper machine, designed for relatively heavy applications of sizing agents to paper of paperboard, usually located between two drier sections, comprising a tub or vat for holding the liquid sizing material, and a set of vertically oriented press rolls the bottom unit of which is usually partially submerged in the sizing material. In the customary operation of a tub-size press, the moving web enters the tub under a dip roll, is totally submerged in the liquid sizing material for a brief period, and then follows the contour of the bottom press roll into the nip of the press in reverse fashion. As it leaves the nip, it follows the contour of the top press roll, and then continues its forward travel into a second drier section. The tub or vat is generally constructed of wood or metal, while the size press unit is usually, but not always, made up of a pair of rolls of differing hardness and composition. Tub-size press units also include such auxiliary elements as pumps, piping, doctor blades, liquid level devices, thermostats, viscosity controllers, spreading rolls, and the like. In addition to tub-size presses on paper machines, such units may also be used with converting or processing machines such as air-driers, impregnators, etc.
Two-Sidedness
The property of having appreciable difference in color or texture between the wire and felt sides. The term is commonly applied to dyed papers, where the felt side is usually darker. It may occur in paper prepared from a mixed furnish of long- and short-fibered stock, the latter being more evident on the felt side, or in filled sheets, where more pigment is retained on the felt side.
Uniformity
The quality of being uniform in some property, such as color, finish, or especially formation and evenness of fiber distribution.
Unsized
Not having been treated with size – either during or after manufacture. Water absorbent.
Vellum Finish
An uncoated paper finish that is fairly even but not quite as even as a smooth finish.
Virgin Stock
Pulp that has not previously been used in the papermaking process. It is to be distinguished from secondary stock.
Wax Pick Test
Test to determine the resistance of the surface layer of a sheet to the breakaway of surface fragments, when the sheet is separated from the inked plate or blanket in the printing process.
Web
The sheet of paper coming from the paper machine in its full width or from a roll of paper in any converting operation.
Wet End
That portion of the paper machine between the headbox and the drier sextion.
Wet Mullen
The Mullen bursting strength of paper or paperboard after complete saturation with water.
Wet Tensile Strength
The tensile strength of paper after it has been wetted with water under specified conditions.
Yield
The amount of a substance usually expressed as a percentage of starting material that remains after a processing action. In papermaking, examples are the pulp obtained from pulpwood, the amount of paper from pulp, the amount of shipped paper from manufactured paper, etc.
Z-Direction Tensile Strength
The tensile strength perpendicular to the plane of the sheet. It is used as a measure of bonding strength.
