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
Textile Manufacturing or Textile Engineering is a major industry. It is largely based on the conversion of fibre into yarn, then yarn into fabric. These are then dyed or printed, fabricated into cloth which is then converted into useful go ...
to change the absorption and wear characteristics of those materials.
Sizing is used for oil-based surface preparation for
gilding
Gilding is a decorative technique for applying a very thin coating of gold over solid surfaces such as metal (most common), wood, porcelain, or stone. A gilded object is also described as "gilt". Where metal is gilded, the metal below was trad ...
(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 visual art, 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 i ...
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, Textile, rags, poaceae, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre e ...
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 measure ...
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
A blot, in molecular biology and genetics, is a method of transferring proteins, DNA or RNA onto a carrier (for example, a nitrocellulose, polyvinylidene fluoride or nylon membrane). In many instances, this is done after a gel electrophoresis, t ...
. Slack sized paper is somewhat absorbent and includes
newsprint, 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,
ledger, 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 diets ...
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 ...
(water-loving) and
hydrophobic (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
Succinic anhydride, is an organic compound with the molecular formula (CH2CO)2O. This colorless solid is the acid anhydride of succinic acid.
Preparation
In the laboratory, this material can be prepared by dehydration of succinic acid. Such ...
(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 alk ...
(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
Gelatin or gelatine (from la, gelatus meaning "stiff" or "frozen") is a translucent, colorless, flavorless food ingredient, commonly derived from collagen taken from animal body parts. It is brittle when dry and rubbery when moist. It may also ...
, 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
Gilding is a decorative technique for applying a very thin coating of gold over solid surfaces such as metal (most common), wood, porcelain, or stone. A gilded object is also described as "gilt". Where metal is gilded, the metal below was trad ...
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 manufac ...
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 longitudin ...
machine. On the weaving machine, the warp yarns are subjected to several types of actions i.e. cyclic strain, flexing, abrasion at various
loom 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 diets ...
,
polyvinyl alcohol (PVA),
carboxymethyl cellulose (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 p ...
,
polyester,
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.
See also
*
Preservation (library and archival science)
In Library science, library and archival science, preservation is a set of preventive conservation activities aimed at prolonging the life of a record, book, or object while making as few changes as possible. Preservation activities vary widely ...
*
Acid-free paper
*
Textile manufacturing
Textile Manufacturing or Textile Engineering is a major industry. It is largely based on the conversion of fibre into yarn, then yarn into fabric. These are then dyed or printed, fabricated into cloth which is then converted into useful go ...
*
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