Wheatpasting

Wheat paste (also known as flour paste, or simply paste) is a gel or liquid adhesive made from wheat flour or starch and water. It has been used since antiquity for various arts and crafts such as book binding,découpage, collage, papier-mâché, and adhering paper posters and notices to walls. Closely resembling wallpaper paste, a crude wheat flour paste can be made by mixing roughly equal portions of flour and water and heating until the mixture thickens.

A critical difference among wheat pastes is the division between those made from flour and those made from starch. Vegetable flours contain both gluten and starch. Over time the gluten in a flour paste cross-links, making it very difficult to release the adhesive. Using only starch, a fine quality, fully reversible paste can be produced. The latter is the standard adhesive for paper conservation.

Besides wheat, other vegetables also are processed into flours and starches from which pastes can be made: characteristics (e.g. strength, reversibility) vary with the plant species, manufacturer's processing, and recipe of the end-user.

A common use is to make chains of paper rings made from colored construction paper. It can also be used to create papier-mâché.

In the fine arts, wheat starch paste is often used in preparation and presentation. A good wheat starch paste has a strength compatible with many paper artifacts, remains reversible over time, is neither too acidic or alkaline, and is white.

Activists and various subculture proponents often use this adhesive to flypost propaganda and artwork. It has also commonly been used by commercial bill posters since the nineteenth century. In particular, it was widely used by nineteenth and twentieth century circus bill posters, who developed a substantial culture around paste manufacture and postering campaigns. In the field of alcohol and nightclub advertising, in the 1890s, Henri de Toulouse-Lautrec's posters were so popular that instructions were published on how to peel down the pasted posters without damage.

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