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| Porcupine, 1951, woodcut by Leonard Baskin |
All works on paper have special needs; some problems, such as the damage caused by sunlight, have been touched on above, but this needs emphasis, and other risks need to be mentioned. Whether used for drawings, watercolours, prints or books, the healthy survival of paper, or otherwise, depends upon its quality. Until the early nineteenth century paper was made from linen rags, and the cellulose content in linen meant that added chemicals were unnecessary: this type of paper is the most resilient.
Paper made from wood pulp, as much was from the 1840s onwards, included lignin, an acidic light-sensitive substance which eventually turns the paper brown and brittle, while certain methods of sizing paper, and bleaching it, have also caused susceptibility to damage.
