Paper

Ingredients and properties of paper

The type of plant fibres and the method of manufacture determine, to a large degree, the final characteristics of the paper. The most permanent papers are those made from plant fibres which are high in cellulose, such as cotton. A large percentage of the paper produced today is made from ground wood. This paper is not intended to last and is used for ephemera, such as newspapers. Different quality wood-based paper products are available; and high-quality, long-lasting papers can be produced from wood pulp.

• Besides fibres and water, paper usually contains products that are added during manufacture to give it certain properties. These include:

• fillers or loadings that produce a smoother surface and a whiter, more opaque paper. Kaolin or China clay, calcium carbonate and titanium dioxide have been used as fillers and loadings;

• coatings that are added to the surface of the paper to alter its characteristics. Minerals and other materials such as starch have been used as coatings; and

• sizes to reduce the absorbency of paper. Historically, gelatine was used as a size in European paper-making.

Most papers also contain impurities and unwanted chemicals—acids—that limit their lifespan. These acids are a major cause of deterioration and impermanence in paper. They can migrate from one paper to another, plus paper will pick up acids from other materials it touches. To overcome the problem with acids, there are now papers and paper-based products being produced that are free of acids and other impurities. These archival-quality products are made from various fibres, including cotton and specially-treated wood pulp. Many archival papers and boards also contain an alkaline buffer to help protect them from acidity.

Whenever possible, use archival papers to store and display other paper items.