The type of support that you choose is as important as the pencil used.
Most of us have come across a paperback book whose pages have yellowed, or even worse, are brittle and crumble. This is what can happen to artwork if an acid-free or archival paper is not used.
Artists use acid-free or archival paper because it offers chemical stability and physical durability. It will not yellow, it will not cause chemical reactions over time with colored pencils like regular paper will.
Some definitions for you to throw around at your next party:
- acid-free: paper that can be made from any cellulose fiber as long as the active acid pulp is eliminated during the process. The paper will contain a neutral or basic pH when infused with water if it is acid-free.
- lignin: a brown organic substance that binds to cellulose fibers and hardens and strengthens the cell walls of plants. It is a major contributor to the chemical degradation of paper. As it deteriorates, lignin causes papers to yellow and become brittle.
- alkalinity: the overall capacity of a water solution to neutralize an acid.
- archival: a permanent, durable acid-free paper. Archival paper can be broken into two categories:
- conservation-grade: acid-free, buffered paper made from wood-based pulp
- archival- or museum-grade: cotton rag paper made from cotton pulp.
Chemicals can be added to slow down pH changes that occur over time. A paper labeled 'acid-free' is actually acid neutral. This treatment will wear off over time and the paper (and your artwork) will begin to deteriorate. An archival-quality paper will last the longest.
Usually, calcium or magnesium bicarbonate is used to neutralize the natural acids in wood pulp during manufacturing. A lot more than what is needed is used to provide protection from further acids remaining in the paper or in the environment. In order for a paper to last at least 100 years, it must have an alkaline reserve of 2% or more.
According to the ASTM D 3290-00, an alkaline paper has a life expectancy of over 1,000 years for the best paper and 500 years for average grades.