Fine art prints are printed on archival quality paper that will last at least 100 years. The paper is tough and strong and used by leading artists for their works on paper and limited edition prints. Physical strength for the paper is ensured by using a long, high quality fibre such as cotton or flax. Paper of this type is often made using cotton rags, and hence is called “rag paper”.
The reason why the paper in good books from the mid 1800s and earlier is not brittle or discoloured, while paper in newspapers or books less than 20 years old is yellow and brittle, is that the former are made with quality acid-free rag/cotton paper while the latter are made with acid woodchip paper.
Archival paper is specially made to have chemical and physical properties that ensure it remains useable for long periods. Acids damage paper and cause it to deteriorate. The environment we live in is slightly acidic, so paper makers counter this by making the paper pulp slightly alkaline rather than neutral. Calcium carbonate, an alkaline buffer, is added for this purpose; it also acts as a filler to make the paper more opaque.
There are also extraneous materials (such as sugars, starches and gums) in the pulp that can cause discolouring and deterioration, so these need to be carefully removed during paper making.
Arches and Rives papers, made in France, are some of the best known printmaking papers. Most of the papers from this company are acid-free and made of from natural flax, cotton or esparto fibres; many are 100% cotton. All Arches papers are manufactured on a cylinder mould, as they have been for more than a hundred years. This process, in which the pulp gradually settles and drains on a slowly rotating screen-covered cylinder, results in a paper that has an attractive handmade look and feel.
Once paper has been made to archival standards, it still requires proper storage for permanence. Wrapping and packaging materials should be acid-free, and acid-free storage boxes are a good investment.