Sizing

Surface sizing agents are amphiphilic molecules, having both hydrophilic (water-loving) and hydrophobic (water-repelling) ends.

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.

Usual internal sizing chemicals used in papermaking at the wet end are alkyl ketene dimer (AKD) and alkyl succinic anhydride (ASA) in neutral pH conditions, and the more ancient rosin system which requires acidic conditions and is still used in some mills.

"[3] 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.

Many books of the fifteenth century were printed upon paper that had not been sized, this extra treatment not being essential for a type impression.

The sizing was accomplished by a worker holding a number of sheets by the aid of two wooden sticks, and dipping the paper into the warm gelatinous liquid.

"[5] In the field of library preservation it is known "that acid hydrolysis of cellulose and related carbo-hydrates [sic] is one of the key factors responsible for the degradation of paper during ageing.

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.

Different types of water soluble polymers called textile sizing agents/chemicals such as modified starch, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), and acrylates are used to protect the yarn.

Aqueous glue, frequently the hide glue was used for sizing the canvas for centuries,[13] Size in art is not a replacement for ground: it is not intended to form a level surface for painting, it is used to simply fill pores and isolate the canvas from the actual ground.