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Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorption and wear characteristics of those materials. Sizing is used for oil-based surface preparation for gilding (sometimes called ''mordant'' in this context). It is used by painters and artists to prepare paper and textile surfaces for some art techniques. Sizing is used in
photography Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is emplo ...
to increase the sharpness of a print, to change the glossiness of a print, or for other purposes depending on the type of paper and printing technique. Fibers used in
composite materials A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...
are treated with various sizing agents to promote adhesion with the matrix material. Sizing is used during
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distribu ...
manufacture to reduce the paper's tendency when dry to absorb liquid, with the goal of allowing inks and paints to remain on the surface of the paper and to dry there, rather than be absorbed into the paper. This provides a more consistent, economical, and precise printing, painting, and writing surface. This is achieved by curbing the paper fibers' tendency to absorb liquids by capillary action. In addition, sizing affects abrasiveness, creasability, finish, printability, smoothness, and surface bond strength and decreases surface
porosity Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measur ...
and fuzzing. There are three categories of papers with respect to sizing: ''unsized'' (''water-leaf''), ''weak sized'' (''slack sized''), and ''strong sized'' (''hard sized''). Waterleaf has low water resistance and includes absorbent papers for blotting. Slack sized paper is somewhat absorbent and includes
newsprint Newsprint is a low-cost, non-archival paper consisting mainly of wood pulp and most commonly used to print newspapers and other publications and advertising material. Invented in 1844 by Charles Fenerty of Nova Scotia, Canada, it usually has a ...
, while hard sized papers have the highest water resistance, such as coated fine papers and liquid packaging board. There are two types of sizing: ''internal sizing,'' sometimes also called engine sizing, and ''surface sizing'' (tub sizing). Internal sizing is applied to almost all papers and especially to all those that are machine made, while surface sizing is added for the highest grade
bond Bond or bonds may refer to: Common meanings * Bond (finance), a type of debt security * Bail bond, a commercial third-party guarantor of surety bonds in the United States * Chemical bond, the attraction of atoms, ions or molecules to form chemical ...
,
ledger A ledger is a book or collection of accounts in which account transactions are recorded. Each account has an opening or carry-forward balance, and would record each transaction as either a debit or credit in separate columns, and the ending or ...
, and writing papers.


Surface sizing

Surface sizing solutions consist of mainly modified
starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human die ...
es and sometimes other hydrocolloids, such as gelatine, or surface sizing agents such as acrylic co-polymers. Surface sizing agents are amphiphilic molecules, having both
hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are n ...
(water-loving) and
hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, ...
(water-repelling) ends. The sizing agent adheres to substrate fibers and forms a film, with the hydrophilic tail facing the fiber and the hydrophobic tail facing outwards, resulting in a smooth finish that tends to be water-repellent. Sizing improves the surface strength, printability, and water resistance of the paper or material to which it is applied. In the sizing solution, optical brightening agents (OBA) may also be added to improve the opacity and whiteness of the paper or material surface.


Internal sizing

Internal sizing chemicals used in papermaking at the wet end are alkyl succinic anhydride (ASA),
alkyl ketene dimer Alkyl ketene dimers (AKDs) are a family of organic compounds based on the 4-membered ring system of oxetan-2-one, which is also the central structural element of propiolactone and diketene. Attached to the oxetane ring of technically relevant al ...
(AKD) and rosin. By making the paper web more hydrophobic, the sizing agents influence dewatering and retention of fillers and fibers in the paper sheet. Next to paper quality, internal sizing agents' main effect is on runability of the paper machine.


Preservation

While sizing is intended to make paper more suitable for printing, it also makes printing paper less durable and poses a problem for preservation of printed documents. Sizing with starch was introduced quite early in the history of papermaking. Dard Hunter in ''Papermaking through Eighteen Centuries''Dard Hunter, ''Papermaking through Eighteen Centuries''. (New York: William Edwin Rudge, 1930), 141
available on line
corroborates this by writing, "The Chinese used starch as a size for paper as early as A.D. 768 and its use continued until the fourteenth century when animal glue was substituted." In the early modern paper mills in Europe, which produced paper for printing and other uses, the sizing agent of choice was gelatin, as Susan Swartzburg writes in ''Preserving Library Materials: "Various substances have been used for sizing through the ages, from gypsum to animal gelatin." Hunter describes the process of sizing in these paper mills in the following: With the advent of the mass production of paper, the type of size used for paper production also changed. As Swartzburg writes, "By 1850 rosin size had come into use. Unfortunately, it produces a chemical action that hastens the decomposition of even the finest papers." In the field of library preservation it is known "that acid hydrolysis of cellulose and related carbo-hydrates icis one of the key factors responsible for the degradation of paper during ageing." Some professional work has focused on the specific processes involved in the degradation of rosin-sized paper, in addition to work on developing permanent paper and sizing agents that will not eventually destroy the paper. An issue on the periphery to the preservation of paper and sizing, is washing, which is described by V. Daniels and J. Kosek as, "The removal of discolouration ... in water is principally effected by the dissolution of water-soluble material; this is usually done by immersing paper in water." In such a process, surface level items applied to the paper, such as size in early paper making processes as seen above, have the possibility of being removed from the paper, which might have some item specific interest in a special collections library. With later processes in paper making being more akin to "engine sizing," as H. Hardman and E. J. Cole describe it, "Engine sizing, which is part of the manufacturing process, has the ingredients added to the furnish or stock prior to sheet formation," the concern for the removal of size is less, and as such, most literature focuses on the more pressing issue of preserving acidic papers and similar issues.


Gilding

Sizing is a term used for any substance which is applied to a surface before gilding in order to ensure adhesion of the thin gold layer to the substrate. Egg whites have often been used as sizing; the Ancient Egyptians sometimes used blood. Other commonly used traditional materials for gold leaf sizing are rabbit-skin glue diluted and heated in water (water gilding), and boiled linseed oil (oil gilding); modern materials include
polyvinyl acetate Polyvinyl acetate (PVA, PVAc, poly(ethenyl ethanoate)), commonly known as wood glue, PVA glue, white glue, carpenter's glue, school glue, or Elmer's glue in the US, is a widely available adhesive used for porous materials like wood, paper, and ...
.


Textile warp sizing

Textile warp sizing, also known as tape sizing, of warp yarn is essential to reduce breakage of the
yarn Yarn is a long continuous length of interlocked fibres, used in sewing, crocheting, knitting, weaving, embroidery, ropemaking, and the production of textiles. Thread is a type of yarn intended for sewing by hand or machine. Modern manu ...
and thus production stops on the
weaving Weaving is a method of textile production in which two distinct sets of yarns or threads are interlaced at right angles to form a fabric or cloth. Other methods are knitting, crocheting, felting, and braiding or plaiting. The longitudinal ...
machine. On the weaving machine, the warp yarns are subjected to several types of actions i.e. cyclic strain, flexing, abrasion at various
loom A loom is a device used to weave cloth and tapestry. The basic purpose of any loom is to hold the warp threads under tension to facilitate the interweaving of the weft threads. The precise shape of the loom and its mechanics may vary, but t ...
parts, and inter yarn friction. With sizing, the strength—abrasion resistance—of the yarn will improve and the hairiness of yarn will decrease. The degree of improvement of strength depends on adhesion force between fiber and size, size penetration, as well as encapsulation of yarn. Different types of water soluble polymers called textile sizing agents/chemicals such as modified
starch Starch or amylum is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. This polysaccharide is produced by most green plants for energy storage. Worldwide, it is the most common carbohydrate in human die ...
,
polyvinyl alcohol Poly(vinyl alcohol) (PVOH, PVA, or PVAl) is a water- soluble synthetic polymer. It has the idealized formula H2CH(OH)sub>''n''. It is used in papermaking, textile warp sizing, as a thickener and emulsion stabilizer in polyvinyl acetate (PVAc) ...
(PVA),
carboxymethyl cellulose Carboxymethyl cellulose (CMC) or cellulose gum is a cellulose derivative with carboxymethyl groups (-CH2-COOH) bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone. It is often used as its sodiu ...
(CMC), and acrylates are used to protect the yarn. Also wax is added to reduce the abrasiveness of the warp yarns. The type of yarn material (e.g.
cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...
,
polyester Polyester is a category of polymers that contain the ester functional group in every repeat unit of their main chain. As a specific material, it most commonly refers to a type called polyethylene terephthalate (PET). Polyesters include natura ...
,
linen Linen () is a textile made from the fibers of the flax plant. Linen is very strong, absorbent, and dries faster than cotton. Because of these properties, linen is comfortable to wear in hot weather and is valued for use in garments. It also ...
), the thickness of the yarn, and the type of weaving machinery will determine the sizing recipe. Often, the sizing liquor contain mutton tallow. Mutton tallow is an animal fat, used to improve abrasion resistance of yarns during weaving. The sizing liquor is applied on warp yarn with a warp sizing machine. After the weaving process the fabric is desized (washed). Sizing may be done by hand, or in a
sizing machine Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorption ...
.


See also

* Preservation (library and archival science) *
Acid-free paper Acid-free paper is paper that, if infused in water, yields a neutral or basic pH (7 or slightly greater). It can be made from any cellulose fiber as long as the active acid pulp is eliminated during processing. It is also lignin- and sulfur-fre ...
* Textile manufacturing * Paper chemicals * Surface chemistry of paper *


References


External links


History, Chemistry, and Long-Term Effects of Alum-Rosin Size in Paper


{{Authority control Papermaking Weaving