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Paper Grades And Definitions

( Originally Published 1920 )

WHEN starting to write this chapter the main object was to give the reader a general idea of the variety of products made by the paper industry and the multiplicity of their uses. A mere list of names would be of some help, but it would be insufficient, and might even be misleading in some cases; for example, "chipboard" is not a board made from chips, and "fish paper" has nothing to do with fish, but is used in electrical work. Rating the products ac-cording to their price range would also be unsatisfactory, for this is constantly changing according to economic conditions. Use considerations seems about as bad as a list of names, for it tells very little because one paper may serve so many purposes, or so many different papers may be used for the same work. Classification according to physical and chemical properties is objection-able because there are so many intangible characteristics in paper which are not subject to close definition. Finally the list might be made on the basis of the history of the papers, such as the raw material used, the manufacturing processes employed and the type of equipment and paper machine employed. This would lead to endless complications and because of rapid changes in methods of manufacture it would soon be obsolete.

Since no one of these methods seemed entirely suitable a little has been taken from each and the following list of products and definitions made up on the "hit-or-miss" basis. In doing this, great help was obtained from "The Dictionary of Paper," published by the American Paper and Pulp Association in 1951, and from `A Dictionary of Paper and Paper-Making Terms" by E. J. Labarre published in Amsterdam in 1937. No claim is made that the information which follows covers the field at all completely, but it is safe to say that the errors of omission are more numerous than those of commission. To make it as complete as might be desired would be to duplicate the dictionaries cited. It is hoped that it may be of some help to the uninitiated reader.

ABRASIVE PAPERS. Heavy, strong, hard-sized rope or kraft paper, coated on one side with glue and some abrasive material, such as flint, garnet, aluminum oxide or silicon carbide, in varying degrees of fineness to suit the work to be done. For wet use the adhesive may be a varnish-resin compound. Sold under various trade names as Sand paper, Flint paper, Emery paper, Garnet paper, Carborundum paper, etc.

ABSORBENT PAPERS. Soft, loosely felted, unsized, spongy papers which have the property of absorbing water or special chemicals. Included are blottings, filter papers, toweling, matrix paper and papers used for impregnating with resins, for vulcanizing, and for the manufacture of vegetable parchment.

ALBUM PAPER. A heavy cover paper made in solid colors, especially black and gray, and used in photographic albums. It requires a soft surface which will take paste without cockling, and freedom from materials which will discolor prints.

ALKALI-PROOF PAPER. A paper, either white or colored, which does not discolor when in contact with alkaline materials, such as soap. Careful selection of fibers and coloring matters is necessary, but no particular strength requirements need be met. Many book papers are sufficiently alkali-proof and glassine and waxed papers are also satisfactory.

ANTIQUE PAPERS. Any paper with a rough surface resulting from the use of press felts with long nap, and run with little pressure on the presses and calenders. No particular fiber furnish is implied by this name.

ANTI-TARNISH PAPER. A term originally applied to tissues used for wrap-ping silverware, but now used for all papers so prepared that they will not rust or discolor razor blades, needles, silverware, etc. Various fibers are used and weights of paper made; the chief requirements are freedom from acidity and reducible sulfur compounds. Copper salts or other inhibitors are sometimes used for silver tissues.

ART PAPER. An English term applied to a coated paper or board. In America it may mean a coated paper or a drawing paper with a high finish and smooth surface.

ASBESTOS PAPER. A fire retardant and heat insulating paper made chiefly from asbestos fiber on a cylinder machine. Generally not over 0.06 of an inch thick.

ASPHALT PAPERS. Under this term are included papers which are coated, saturated or laminated with asphalt or similar bituminous material. Among them are sheathing paper saturated with asphalt; duplex water-proof which consists of two sheets of paper made to adhere by a layer of asphalt; house sheathing paper which is saturated with more than its own weight of asphalt, then coated on both sides with asphalt and finally dusted with talc; roofing paper, which is generally a soft, porous, rag paper saturated and coated with asphalt and with crushed slate or other grit embedded in the asphalt surface.

BAG PAPER. Paper used for making bags for use by grocers is normally of kraft paper, the weight depending on the size of the bag. Many other types of paper are employed for other kinds of bags, such as greaseproof for salted nuts; water resistant paper for garbage bags; bleached paper for candy bags, etc. The term does not denote any one kind of paper or any special strength requirement.

BARYTA PAPER. A paper coated with barium sulfate to give a smooth, low-gloss surface; used chiefly as a base for photographic emulsions.

BASIC SIZE. The trade custom for size of sheet and number of sheets in a ream; it is used for calculating the basis weight. A few of the specifications are as follows: 25 x 38 inches, 500 sheets for Bible, book, gummed and offset papers. 24 x 36 inches, 500 sheets for glassine, news, hanging, poster, tissue, waxing, and wrapping papers. 20 x 26 inches, 500 sheets for cover and box cover papers. 17 x 22 inches, 500 sheets for bond, ledger, manifold, mimeograph, railroad manila and writing papers.

BASIS WEIGHT. The weight in pounds for a ream of paper cut to a definite sizeógenerally that noted under "Basic Size." " In Europe and South America the weight is expressed in the metric system as grams per square meter (1 gm. per sq. m. = 0.678 lb. per rm.-25 x 38-500).

BIBLE PAPER. An opaque, light weight, printing paper for use where low bulk is an essential, as in Bibles, insurance rate books, encyclopedias, etc. The basis weight is generally from 14 to 30 pounds (25 x 38-500); the preferred fiber stock is linen or hemp, very carefully beaten to fibrillate rather than cut it; and titanium dioxide is often used as a filler. This type of paper was developed in England and first known as Oxford India paper.

BLANKS. A name applied to thick cardboards, coated or uncoated, pasted or unpasted, and made in standard thicknesses with either white or colored liners. They should have maximum smoothness of surface and stiffness. They range from 0.012 to 0.078 of an inch with corresponding ream weights of 120 to 775 pounds (22 x 28-500). Their use is for calendar backs, signs, and window displays.

BLOODPROOF PAPER. A strong wrapping paper, hard sized with wax, or otherwise treated, to render it resistant to blood; used in stores on scales where meat is weighed, and for separating layers of meat in a package.

BLUEPRINT. The base stock for blueprint paper must be well-formed and have a good surface, good wet strength and, even though well sized, have a uniform surface absorbency. A prime essential is freedom from chemicals which would affect the sensitizing materials. Good papers of this type cannot be made without special precautions in the paper mill.

BOARDS. The difference between paper and boards is not sharply defined, but in general boards are heavier, thicker and more rigid than papers. The varieties of board are almost as numerous as those of paper, and they may be made on either a cylinder or a fourdrinier machine. The materials used in their manufacture are extremely varied and many are not sufficiently purified for use in high grade papers. Boards are known by various names which may indicate the name of the material used, the purpose served, the nature or appearance of the board, the name of the inventor, or even some fancy name. On the other hand the name may be misleading as, for example, "chipboard" which is not made from chips, but from old waste papers. Boards are seldom specified by ream weight, but are designated by their thickness in "points," a point being a thousandth of an inch. They are used for innumerable purposes, with appropriate specific names.

BOCUS. A term indicating that the product is made from inferior materials in imitation of higher grades of paper or board. It is applied to many different types of paper, as "bogus manila," "bogus bristol," etc.

BOND. Originally this term was applied to papers of high strength, permanence and durability such as those used for government bonds and legal papers. It now includes a wider variety of papers for business letterheads, forms, etc. Bond papers are essentially writing papers, so they must take ink well and have good erasing properties, but as most of their uses involve some printing, this property is also of importance. The fibers used for the best grades of bond paper are from rags, but many grades are made from high-grade bleached chemical wood pulps.

BOOK PAPER. This general term covers both uncoated and coated papers with the characteristics required for printing purposes, with the exception of newsprint. The fiber composition, the weight per ream and the surface finish vary greatly and are adjusted to suit the kind of printing to be done and the requirements of the particular job.

BREAD WRAPPERS. A thin, waxed paper, generally made opaque by titanium dioxide and printed with the desired characters. The basis weight is about 30 to 35 pounds, including 9 to 10 pounds of wax, and the paper is sold in sheets or rolls.

BRISTOLS. A name given to a cardboard of 6 points or more. First made as a pasted board in Bristol, England.

BUILDING PAPERS. Papers produced from strong fibers ranging from rags to pulp screenings, and used in the construction of buildings as sheathing and under floors.

CABLE PAPER. A strong paper suitable for cutting into narrow strips and winding on wire as insulation. High tensile strength is essential.

CANDY TWISTING TISSUE. A light-weight paper, generally waxed for wrap-ping candy kisses, taffy, etc.

CARBON TISSUE. A tissue of 4 to 10 pounds weight, used for coating with carbon black or other coloring matter in a vehicle which is usually wax or oily material. The final paper is CARBON PAPER and is used for making duplicate copies by pen, pencil or typewriter.

CARTRIDGE PAPER. Paper employed for making the tubular section of shot-gun shells. It is made on a cylinder machine, from 0.008 to 0.012 of an inch thick, unsized and lightly calendered.

CATALOG PAPER. A light paper, either English finish or coated, usually made with a considerable proportion of groundwood, and used for mail-order catalogs, telephone directories, etc. Uniformity of weight, opacity, finish and formation are requisites.

CHART PAPER. A paper with the characteristics of bond or ledger papers. It must have good printing and erasing properties and low expansion and contraction with changing humidities. Used for making charts and graphs.

CHECK PAPER. A bond paper often treated with chemicals or dyes to make alteration of writing difficult or impossible.

CHROMO PAPER. Any paper or board which is especially suitable for printing with colors; the term is generally applied to coated papers.

CIGARETTE PAPER. A strong tissue of uniform, close texture, used to cover the tobacco in cigarettes. It is generally made from linen or flax tow which has been very highly beaten, and usually contains from 15 to 30 per cent of calcium carbonate filler.

COARSE. This term applies to wrappings, towels, tags, toilet tissues, gummed tape, etc., to distinguish them from FINE PAPERS, which include book, bond, ledger and cover papers.

COATED. A term applied to any paper or board whose surface has been covered with a coat of adhesive and mineral pigment. The term is some-times applied to lacquered and varnished papers.

CONDENSER TISSUE. A very thin paper of uniform thickness, good formation, and especially free from conducting particles. Used as a dielectric between the foils of condensers.

CORRUGATED PAPER. Paper which has been passed through rolls with alternate ridges and grooves which run in mesh with each other, and give the paper a permanently fluted contour. Such paper or board may be used as a wrapping or it may be faced on one or both sides to form a sturdier structure for heavier packing or cartons.

CREPED PAPER. Paper which is given a rough, crimped surface by crowding it against a doctor blade on a press during its manufacture, generally while in the wet condition. The process shortens the web in the direction of its length and produces a soft, pliable sheet which will stretch very greatly before breaking.

CURRENCY PAPER. A bond type paper used for printing currency, bonds and government securities. In the United States it is made from new rag cuttings, is tub sized with glue, loft dried and plate finished. It must have high tensile and folding strength and exceptional resistance to wear.

DEADENING FELT. A very heavy paper made from rags and old papers and used in construction work to keep out drafts and deaden sounds.

DECALCOMANIA PAPER. An unsized paper of smooth, uniform finish, used as a base for the decalcomania coatings of starch and gum arabic. After printing the print may be transferred by soaking the paper in water, and slipping the print with its gum backing onto the article to be decorated.

DECKLE EDGE. The feathery, untrimmed edge of a sheet of paper formed by the flow of the stock against the deckle strap, or imitated by means of a jet of air or water. The term is also applied to paper showing such an edge.

DRAWING PAPER. A general term applied to paper used for pen or pencil drawing. There are numerous grades for different types of work and the fiber composition ranges all the way from rag stock to groundwood.

DUPLEX. A term applied to papers or boards differing in color, finish, or texture on the two sides. Such differences may be obtained on the paper machine, during finishing, or by pasting.

EGG-CARTON BOARD. A board made from old papers used for making car-tons for holding eggs. It must have good folding properties.

EMBOSSED. A term applied to a paper or board on which a design has been impressed by passing between an engraved roller and one of soft, compressible material. The effect is also obtainable by pressing the paper between strong, coarse fabrics.

ENVELOPE PAPER. Because of the wide variety of envelopes, this term covers a large number of grades of paper which fulfill the demands for strength and writing qualities.

FEATHERWEIGHT. A term applied to light weight papers, but more especially to those of extreme lightness in proportion to bulk.

FILTER PAPER. An unsized, porous paper used for the separation of solid particles from fluids or gases. It comes in many grades of porosity, chemical purity and fiber furnish according to the work it has to do.

FINE PAPERS. Papers of the grades used for writing and for book printing. Included are bond, ledger, cover and book papers.

FIREPROOF. A term applied to paper so treated that it will not burn with a flame, though it will char.

FLINT GLAZING. A method of imparting a very high polish to paper, especially coateds, by rubbing with a smooth, polished flint.

FLOCK PAPER. Paper prepared by covering the whole or a part of its surface with an adhesive and dusting the surface while sticky with powdered fibers of various kinds.

FLY PAPER. Paper coated with a permanently sticky material to kill flies by entanglement; or treated with a poisonous substance and a fly attractant, to kill by poisoning.

FOIL PAPER. A paper to which a metal foil is laminated.

FOLDER STOCK. Board or bristol of high tearing strength and stiffness, and good folding properties; used for folders in filing cabinets, etc.

FRUIT WRAP. A lightweight tissue used for wrapping fruit for shipment. Sometimes treated chemically to retard decay of the fruit with which it is in contact.

GLASSINE. A very dense, semitransparent paper, generally made from chemical woodpulp which is beaten to give a high degree of hydration. The paper is grease resistant, not readily penetrated by air, and if waxed is highly resistant to moisture vapor. It is used to wrap foods, tobacco, chemicals, etc., and for purposes where transparency is helpful.

GRANITE PAPER. A paper containing a small percentage of deeply dyed fibers to give a characteristic mottled effect.

GREASEPROOF. Any paper which has been treated in any way during its manufacture to make it resistant to the penetration of grease or oil.

GROUNDWOOD PAPERS. Any paper containing a substantial proportion of mechanical wood pulp. Standard newsprint contains 70 per cent or more, and groundwood book papers from 20 to 75 per cent.

GUMMED PAPER. Any paper coated on one side with an adhesive, such as fish glue, dextrin or animal glue. Various kinds of paper are used according to the use requirements such as labels, sealing tape, etc.

HANGING PAPER. The raw stock used in making wall paper. The converter usually coats it with a ground coat of clay, and then prints it with any decorative design desired.

HEAT-SEALING PAPERS. Papers coated or impregnated with material which becomes adhesive on the application of heat. Paraffin waxed paper is self-sealing; varnished or lacquered papers may be made heat sealing by proper additions to the lacquer; and papers coated with resin compositions which are activated by heat are widely used.

IMITATION ART. Printing paper with a high finish, prepared by loading very heavily with clay and calendering very hard, usually with a water finish.

INSULATING BOARD. A type of board used for interior walls and ceilings. It should be moisture and fire resistant, have strength but low thermal conductivity, and be insect and vermin resistant. Such boards are made from a large number of fibrous materials and sold under numerous trade names.

JAPAN PAPER. An imitation of the Japanese vellum paper in which the fibers are very long and have a very irregular formation, giving the surface a characteristic mottled effect. Used for greeting cards, novelties and artistic printing of various types. The real Japanese paper is made from very long native fibers, such as paper mulberry, mitsumata, etc.

JUTE PAPER. Any paper made from jute fiber or burlap waste. The fiber is long and the paper has high strength and good folding properties. The name is becoming misleading because of its application to fiber furnishes which contain little or no jute.

KRAFT. A term originally applied to very strong papers made from pulp cooked only lightly by the sulfate process. It has been extended to include all grades of pulp cooked by this process, and to most of the papers made from them, but its most generally understood meaning is that of a heavy, coarse, strong, dark colored paper used chiefly for wrapping purposes.

LAMINATING. In the paper industry this applies to building up a thicker board or paper structure by combining two or more layers with an adhesive.

LEATHERBOARD. A board made for use in shoes as counters, heeling, inner-soles, etc. It may or may not contain leather waste in its fiber furnish.

MACHINE GLAZED. Applies to paper made on a Yankee drier, which has a high glaze on one side and a rough finish on the other.

MANILA. This term originally applied to paper made from manila hemp. It now has no significance as to fiber furnish, but is more often used to designate a color resembling that of the paper originally made from manila hemp rope.

MAP PAPER. Paper used for making maps must be subject to minimum change in dimensions with moisture to avoid poor register of colors. Wet strength properties are often demanded.

MATRIX PAPER. A bulky, absorbent paper used for making molds for casting printing plates. It must have high compressibility and strength when wet, and become rigid and hard when molded and dried. It is sometimes made by allowing a thin web to wind up on the cylinder of a wet-machine and cutting it off when of the proper thickness.

MUSIC-ROLL PAPER. A hard, tough paper resistant to changes in dimension with changing humidity and capable of being perforated cleanly and sharply. Used for player pianos and organs.

NEEDLE PAPER. A black wrapping paper of the anti-tarnish class.

NEWSPRINT. The type of paper used in printing newspapers. Weight per ream 30 to 35 lb. (24 x 36-500); fiber composition at least 70 per cent groundwood and the rest unbleached sulfite.

OATMEAL PAPER. A hanging paper in which fine sawdust is added to the fiber furnish.

OFFSET PAPER. Paper made for printing by the offset lithographic process. It may be coated or uncoated and must be strong enough to resist the pull of the tacky types of ink used.

ONIONSKIN. A lightweight, bond-type, thin and semitransparent paper used for duplicate copies of typed matter to save filing space.

PAPETERIE PAPERS. A class of papers for greeting cards, or for writing, in which case they are usually cut to size, boxed and sold for use in correspondence.

PAPIER-MACHE. Pulp suitable for molding or die-cutting into various articles of commerce. Generally made by boiling waste paper with water and glue and treating the semi-dried product with linseed oil.

PARCHMENT. A sheet of writing material made from the skins of goats or other animals. Vegetable or imitation parchment is made to resemble animal parchment by passing a sheet of unsized, pure fiber paper through a bath of sulfuric acid and then washing it very thoroughly and drying. The acid gelatinizes the surface fibers and the dried surface is grease-proof, has a high wet strength and is very resistant to disintegration by water and many solutions.

PATENT COATED. A term applied to a board which was lined on one or both sides with a white stock while run on a cylinder machine. It is not a coated grade.

PHOTOGRAPHIC PAPER. The base paper for making sensitized paper for photography. It must have good wet strength and exceptional chemical purity as well as very even formation and surface.

PLATE FINISH. The surface obtained by placing sheets of paper between polished sheets of zinc or copper and then passing a pile of these between rolls which apply high pressure. The finish varies greatly with the pressure applied and the number of passes given.

PLAYING-CARD STOCK. A stiff board, usually made by pasting sheets of fourdrinier paper, and given a coating which will take a high polish.

POSTER PAPER. Paper especially suited for billboard work. It must have strength, both wet and dry, be fast in color, and free from curl when wet by the paste used to attach it to the board.

PROOFING PAPER. This term applies to such different products as a high-grade coated for making engraver's proofs, and a cheap book or news-print used for galley proofs.

RAG-CONTENT PAPERS. These contain a minimum of 25 per cent rag fiber. They are usually made with 25, 50, 75 or 100 per cent rag fiber.

REINFORCED PAPER. A duplex, asphalt laminated paper with string, sisal, synthetic fiber or other reinforcing material embedded in the asphalt. Also a paper with cloth on one or both sides.

RICE PAPER. A non-fibrous sheet made from the pith of a tree which is cut into a thin layer of ivory-like texture by means of a sharp knife. Not a true paper.

STRAWROARD. A board made from straw which has been chemically treated, generally with lime, and then made into board as usual. It is a coarse, hard board used for boxes and corrugating purposes.

TISSUE PAPER. In general this term applies to any light, gauzy paper weighing less than 18 pounds (24 x 36-500). Used for many purposes and sold under various names.

TWISTING PAPER. A paper of high tensile strength in the machine direction which is cut into narrow widths and spun or twisted into yarn or twine.

VELLUM. A term used more in respect to finish than as a paper grade. It is generally applied to strong, cream-colored paper made to resemble parchment.

VULCANIZED FIBER. This is a hard, dense board used in electrical work and for boxes, trunks, etc. It is made by treating cotton paper with zinc chloride and winding it up to the desired thickness; it is then cut off, thoroughly washed, dried and finished. Thicknesses up to 2 inches may be produced.

WATER FINISH. A very high finish applied to board or paper by wetting the surface as it passes through the calenders. The surface is not as uniform as that of a supercalendered sheet, but is more compact and glossy.

WAXED PAPER. Paper which has been treated with wax either by passing it through a bath of the wax and at once chilling it by cooling rolls (wet waxing), or by passing through rolls as soon as waxed so that the wax is driven in and the paper feels dry (dry waxing).

WILLESDEN PAPER. Paper made waterproof by immersing in a bath of cuprammonium hydroxide, washing and drying. The treatment partially dissolves and gelatinizes the surface and the final paper is parchment-like, tough, waterproof, rotproof and distasteful to insects. It is used for roof covering and insulating purposes.

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