Sizing

Sizing is a substance that is applied to fibers during paper manufacture in order to curb their tendency to absorb liquids by capillary action. By doing so, sizing keeps the ink on the surface of the paper where it was intended to remain. In addition, sizing affects abrasiveness, creasibility, finish, printability, smoothness, and surface bond strength, and decreases surface porosity and fuzzing.

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There are two major types of sizing: engine (rosin) and surface (tub). Rosin sizing is applied to almost all papers and especially to all those that are machine made, while tub sizing is added for the highest grade bond, ledger, and writing papers. Tub sizing consists of gelatin glue and / or starch and is generally only used for handmade papers. Rosin is an amphipathic molecule, having both hydrophilic (water-loving) and hydrophobic (water-repelling) ends. The rosin coats the paper fiber and forms a film, with the hydrophilic tail facing the fiber and the hydrophobic tail facing outwards. This creates a water-repellent situation, which causes the water-based ink to remain outside on the paper surface.

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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, while hard sized papers have the highest water resistance.

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Fiber: :For other meanings of fiber/fibre please see Fiber (disambiguation)....

Paper: Paper is a thin, flat material produced by the compression of fibres. The fibres used are usually natural and based upon cellulose. The most common material is wood pulp from pulpwood (largely softwood) trees such as spruces, but other vegetable fibre materials including cotton, linen, and hemp may ...

Liquid: A liquid (a phase of matter) is a fluid whose volume is fixed under conditions of constant temperature and pressure; and, whose shape is usually determined by the container it fills. Furthermore, liquids exert pressure on the sides of a container as well as on anything within the liquid itself; this...