Glossary of Key Terms and Abbreviations
Note: Terms listed and defined in this glossary are in boldface. Terms which may be of particular interest to the reader in a given context, but are not listed in the glossary, are in italics.
Sawtimber: Classification of timber inventory that is composed of sawlog-sized trees of commercial species. Sawlogs are logs meeting minimum standards of diameter, length and defect; they include logs at least 8 feet long that are sound and straight, and with a minimum diameter inside the bark of 6" for softwoods and 8" for hardwoods; other combinations of size and defect may be specified by regional standards.
SBS: Solid bleached sulfate paperboard
Scoring: Creasing by mechanical means to facilitate folding and guard against cracking of the paper or board.
Secondary fiber: Recovered paper.
Secondary treatment: Systems use microorganisms to convert the dissolved organic waste in the effluent into a more harmless form. Although primarily designed to remove BOD, secondary treatment also reduces the loading of COD and AOX.
Seconds: Paper that is damaged or has imperfections.
Sedimentation: Deposition of eroded soil into streams or bodies of water. Depending on stream flow and other site conditions, deposited sediment can settle on the stream floor, burying gravels in the streambed and degrading spawning habitat for fish. Elevated sediment concentrations in water can also harm filter-feeding organisms and may interfere with the functioning of the gills of some organisms.
Seed-tree method: Even-aged harvesting/regeneration method in which all of the merchantable timber in a stand is removed in one cutting, except for a limited number of seed trees left singly or in small groups as a seed source to facilitate natural regeneration. These trees typically are harvested after the stand has successfully regenerated.
Selection method: Harvesting/regeneration method used in uneven-aged silviculture in which mature trees are removed, individually (single-tree selection) or in small groups (group selection), from a given tract of forestland over regular intervals of time.
Semi-chemical: Pulp made by a combination of mechanical and chemical processes; typically used to make corrugating medium.
Shade-intolerant species: Tree species (or, more broadly, plant species) that are generally outcompeted in shaded conditions but grow vigorously in full sunlight. Many commercially valuable species, such as loblolly pine and Douglas fir, are shade-intolerant. Because of their preference for light, shade-intolerant species are usually managed using even-aged systems.
Shearing: Site preparation method that involves the cutting of brush, trees or other vegetation at ground level using tractors equipped with angles or V-shaped cutting blades.
Sheet: Term applied to a single sheet, a paper grade or a description of the paper; i.e., coated, uncoated, or offset.
Sheeting: Process of cutting a roll of paper or board into sheets.
Shelterwood method: Removal of the mature timber from a stand in a series of cuttings (usually two) that extend over a relatively short portion of the rotation, in order to encourage the establishment of essentially even-aged reproduction under the shelter of a partial canopy. In irregular shelterwood, the period between the first and second cutting is extended to allow the development of a two-aged stand.
Shrinkage: Decrease in dimensions of a paper sheet; weight loss between amount of pulp used and paper produced.
Silviculture: The art and science of establishing, tending, protecting and harvesting a stand of trees.
Single-tree selection: Method of harvesting in which individual merchantable trees are removed periodically. Natural regeneration is typically relied on to fill in the resulting gaps.
Site preparation: Silvicultural activity to remove unwanted vegetation and other material, and to cultivate or prepare the soil for regeneration.
Size press: Press section of the paper machine, near the end, where sizing agents are added.
Sizing: Process that enables paper to resist penetration by fluids. Sizing can also provide better surface properties and improve certain physical properties of a sheet. The papermaker generally applies either surface or internal sizing, which can be applied as sole treatments or in combination
Skid trail: Temporary, non-structural pathway over forest soil used to drag felled trees or logs to the landing.
Skidding: Short-distance moving of logs or felled trees from the stump to a point of loading.
Slash: See logging debris.
Slice: Device that controls the flow of pulp from the headbox of a fourdrinier paper machine.
Slurry: Watery suspension of fibers or pigment used in papermaking or coating, respectively.
Smoothness: May be measured by the degree of resistance that the paper provides to air moving across its surface. Smoothness influences print quality, ink holdout and transport of paper through machine. The degree of smoothness of an uncoated grade of paper is determined by fiber species, fiber length and finishing processes such as surface sizing and calendering.
Snags: Dead but still standing trees. Snags are important habitat for many species of wildlife: an abundance of invertebrates; birds that construct or nest in cavities and/or feed on the invertebrates; and small mammals that live in the cavities.
Sodium hypochlorite: Bleaching chemical produced by mixing sodium hydroxide and elemental chlorine. Mills are eliminating this chemical from bleaching processes because it produces large quantities of chloroform.
Softwood: Coniferous usually evergreen tree that has needles or scale-like leaves; e.g., pine, Douglas fir and spruce.
Solid board: Paperboard made of only one type of furnish.
Sorted office paper: Paper typically found in offices; may contain a small percentage of groundwood papers such as computer printout and fax paper, but is free of unbleached fiber such as corrugated boxes.
Species diversity: Measure of the abundance and relative frequency of species in a specified area. Species diversity is often used with respect to animal or plant populations in a single stand, but can also be thought of on regional and global scales. For the purposes of biodiversity conservation, spatial scales of species diversity are hierarchical: global diversity is a higher conservation priority than regional diversity, and both are more important than local or stand-level diversity.
Stand: Contiguous group of trees sufficiently uniform in species composition, arrangement of age classes and condition to be a homogenous and distinguishable unit; also the area defined by the extent of those trees.
Starch: Sizing agent usually made from corn and potatoes; improves rigidity and finish by causing fibers to lie flat.
Stem-exclusion stage : The second stage of stand development in a forest, in which the forest canopy closes and the arrival (or recruitment) of new seedlings halts. Because a closed canopy limits the amount of light reaching the forest floor, understory growth is limited, stand vegetation is simpler and species diversity tends to be lower than in other stages.
Stickies: Particles of plastic, adhesives or naturally tacky materials (e.g., pitch from pine trees). embedded in the paper sheet or attached to the forming machine; caused by non-soluble residual particles of hot-melt glues, adhesive labels and other contaminants present in secondary fiber.
Stiffness: Ability of paper to resist deformation under stress and to resist bending stress. It affects how well the paper performs in transport through press and office equipment and during converting. The properties of stiffness are determined by the basis weight and caliper of the paper, the type and quantity of fiber and filler used in the paper, and the degree of fiber bonding.
Stock: (1) Paper or board that is in inventory. (2) Paper or board used in the printing or converting process. (3) Fibrous mixture that is made into paper; also called furnish. (4) Wastepaper.
Stone groundwood pulping (SGW): Processing of press logs against a grindstone while a stream of water wets the stone and removes the pulp. This process has the highest yield 93 - 96% of all pulping processes, but it also produces the weakest pulp.
Streamside management zone (SMZ): May also be called buffer strips or riparian management areas. Zone of forest along a forest stream where management practices that might affect water quality, fish or other aquatic resources are modified. Properly designed SMZs effectively filter and absorb sediments, maintain shade, protect aquatic and terrestrial riparian habitats, protect channels and streambanks and promote floodplain stability. State Best Management Practices generally recommend SMZs, although restrictions and key parameters (e.g., SMZ width) vary.
Strength: Generally three types of strength are measured: folding, tensile and tear. Strength is important so paper can run through machines without tearing and can withstand folding without cracking. A paper's strength is determined by interfiber bonding during sheet formation, fiber strength, the type of fibers and filler in the sheet, basis weight of the sheet and the degree of refining.
Stumpage: Trees "on the stump." Landowners sell these trees to loggers for which they are paid a given price (stumpage price).
Succession: With respect to forest development, succession refers to the changes over time as a forest proceeds from one developmental stage to the next: thus early-successional stands describe stands in the years just after regeneration, while late-successional stands refer to stands in mature or old-growth forests.
Sulfate pulp: See kraft pulp. Pulp produced using an acid cooking solution, usually made from calcium bisulfite and sulfurous acid.
Sulfite pulping: Pulp produced with sulfur dioxide and calcium, magnesium, ammonium or sodium bases. The pulp can be produced at different pH levels. The higher the pH, the stronger the pulp produced. At pH = 14, the strength of sulfite pulp equals that of kraft pulp.
Sulfur dioxide (SO2 ): Chemical compound produced when boilers burn fuel that contains sulfur. Of the fuels used in the paper industry, oil and coal generally contain the highest quantities of sulfur.
Supercalendering: Process that uses alternate metal and resilient rolls to produce a high finish paper separately from the papermaking machine. Supercalendered (SC) papers have been smoothed through an extra calendering phase during papermaking; have clay and other pigments that enhance appearance by adding brightness, smoothness, opacity, strength and bulk.
Surface strength: Cohesiveness of fibers on the surface of a paper.
Surface-sized: Term applied to paper to which a sizing agent has been applied when the paper web is partially dry. The purpose of surface sizing is to increase resistance to ink penetration.
Tack: In printing inks, the property of cohesion between particles. A tacky ink has high separation forces and can cause surface picking.
TAPPI: Technical Association of the Pulp and Paper Industry.
Tear strength: Indicator of the fiber length and the uniformity in refining and formation of a paper sheet. Tear strength is especially important to printers and lithographers. It is determined by a test that measures the average force in grams required to tear a single sheet of paper once the tear has been started.
Tensile strength: Defined as the maximum force required to break a paper strip of a given width under prescribed laboratory conditions; measured as the force (pounds per inch) per unit width of a sample that is tested to the point of rupture.
Text paper: General term applied to various grades of printing papers that are made specifically for books.
Thermomechanical pulp (TMP): Pulp produced from wood chips that have been exposed under pressure to superheated steam. The heat softens the lignin, which allows fiber separation with less damage than in purely mechanical pulping. TMP processes use a refiner that consists of one or two rotating serrated disks to separate the fiber in wood chips. TMP processes reduce the energy requirement of the refining process and increase the strength of the pulp. Typical pulp yields range from 90% to 95%.
Tip fees : Solid waste disposal charges; a refuse collection truck empties or "tips" its load at a landfill, transfer station, or incinerator.
Tissue paper: Paper category characterized by extreme lightness and transparency; basis weight is less than 18 lbs. Tissue paper is used to make napkins, bathroom tissue, paper towels, etc.
Titanium dioxide: Chemical compound used as loading or coating material to increase the whiteness and brightness of a paper sheet and enhance its opacity.
Topliner: Outermost layer of multi-ply paperboard.
Total energy consumption: Energy consumed by the process equipment to produce a ton of pulp or paper.
Totally chlorine-free (TCF): Bleaching process that uses no chlorine-based chemicals.
Total reduced sulfur compounds (TRS): Mix of organic compounds that cause the odor associated with kraft pulp mills. These compounds include hydrogen sulfide, dimethyl sulfide, dimethyl disulfide and methyl mercaptan.
Total suspended solids (TSS): Amount of solids in the effluent. They can eventually settle on the bottom of a mill's receiving water and affect the habitat of bottom-living organisms. Well-operated treatment systems remove most of these solids. Concern remains, however, because heavy metals, dioxins and other unchlorinated compounds can be adsorbed onto the remaining suspended solids.
Toxic equivalence (TEQ): The EPA uses toxic equivalence factors (TEFs) to estimate the relative toxicity of different members of the dioxin and furan families, because they produce similar toxic effects, but at different doses. E.g., TCDD is the most toxic member of the dioxin and furan family and is assigned a toxic equivalence factor of 1.0, while the less toxic TCDF is assigned a toxic equivalence factor of 0.10. Using these factors, the sum of the toxicity of one gram of TCDD and one gram of TCDF would be equal to 1.1 grams TEQ of TCDD.
Twin-wire machine: Paper machine in which pulp slurry is injected between two forming wires, and water is drained from both sides of the paper web.
Two-sidedness: Visual differences between the top (or felt) side of a paper sheet and the bottom (or wire) side.
Unbleached: Paper or paperboard made from unbleached pulp.
Uncoated freesheet: Bleached uncoated printing and writing papers containing not more than 10% groundwood or other mechanical pulp.
Uncoated: Paper or board that has not been coated. Uncoated paper grades are made in a variety of finishes.
Uncoated groundwood papers: Papers containing more than 10% mechanical pulp (stone groundwood, refiner or thermomechanical) in their furnish, excluding newsprint.
Understory: Level of vegetation between the ground and the forest canopy, or overstory.
Uneven-aged management: Class of silvicultural systems that maintain several age classes of trees simultaneously in a forest. In a managed uneven-aged forest, the objective of management is to create and maintain a certain distribution of trees: many more trees are in small size (age) classes than in large ones. The selection method, either single-tree or group selection, is the harvesting/regeneration method used in uneven-aged management.
Volatile organic compounds (VOCs): Broad class of organic gases, such as vapors from solvents and gasoline that react with nitrogen oxides in the atmosphere to form low-level atmospheric ozone .
Washing deinking: Process of removing ink by dewatering pulp.
Web break: Break in a roll of paper while it is on the machine during manufacturing or on the printing press during production.
Web: Continuous sheet of paper produced and rolled up at full width on the paper machine.
Wet end: Beginning of the paper machine where the headbox, forming wire and press section are located.
Wet-strength paper: Paper that retains 15% or more of its dry tensile strength when wet.
Whole-tree harvesting: Practice of removing entire trees at harvest, including tops, limbs, branches, twigs and leaves. In many cases, these trees are chipped whole on site to produce whole-tree chips.
Window envelopes: Envelopes with openings that show the mailing address; openings are either open or covered with plastic or glassine.
Windrowing: Silvicultural activity, associated with intensive site preparation, that removes logging debris and unmerchantable woody vegetation into rows or piles to decompose or be burned.
Wire side: The bottom side of a sheet of paper is the side that has had contact with the wire of the paper machine during manufacture . The wire is a synthetic (often polyester), copper or bronze screen that transports the water and fiber suspension from the wet end to the dry end of a paper machine..
Xerography: Copying process that uses a selenium surface and electrostatic forces to form an image, i.e., "photocopying."
Yarding: Method of transport from harvest area to storage landing.