Editing Sizing (section)

{{Short description|Protective glaze for paper or fabric}}
{{Other uses|Size (disambiguation)}}

'''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 (materials)|filler]] or [[coating|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]]<ref>[https://www.alternativephotography.com/the-sizing-survey-the-results/ Sizing substrates and papers – survey results], alternativephotography.com</ref> 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]] are treated with various sizing agents to promote adhesion with the matrix material.

Sizing is used during [[paper]] 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, [[paper and ink testing|printability]], [[smoothness]], and surface bond strength and decreases surface [[porosity]] 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 paper|blotting]]. 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 paper|bond]], [[ledger]], and [[writing paper]]s.