Volume 17, Number 2
Sep 1993

Greener Papermaking--Is It Good for Permanence?

Reprinted with permission from Paper Conservation News Number 66, June 1993, p. 5-6. Paper Conservation News (PCN) is the quarterly newsletter of the Institute of Paper Conservation, the leading body for professionals concerned with conserving books, archives and works of art on paper. Membership details are available from the Secretary, Leigh Lodge, Leigh, Worcestershire, England, WR6 5LB.

Simon Barcham Green is Director of Barcham Green Company Limited, a company that made paper by hand for 180 years up to 1987. His interest in paper permanence dates back to the early 1960s, and the mill developed the first alkaline watercolor and conservation papers. He was Chairman of the Institute of Paper Conservation from 1988 until April 1993 and is a papermaking consultant, currently working on projects in India and the Philippines.

The last twenty years have seen a huge swing away from acidic, towards alkaline papermaking. It would appear that the scourge of nineteenth and much of twentieth century papermaking may be passing into history. Let us hope so. It should keep paper conservators busy for a century or so yet, at least until all rosin/alum sized paper has either disintegrated or been conserved!

There is also every indication that one of the other key agents of destruction, chlorine and many of its compounds, will soon be a thing of the past. Whilst acid papermaking is dying for economic reasons, chlorine is being killed for ecological ones. In both cases, paper conservators have cause to celebrate. Or have they? Could current technical advance carry other seeds of destruction?

It is interesting to recall that the first warnings of the impact of new papermaking technology on longevity were made in the 1820s and 1830s. The main threats perceived were: Non-rag fibers, rosin sizing and chlorine bleaching. In fact, the problems associated with wood fibers can largely (but certainly not entirely) be overcome by careful and thorough chemical purification and the avoidance of the other two threats. Furthermore, it seems likely that modern papermaking so thoroughly removes chlorine residues that this may not be a problem in most papers.

The paper industry's trade and technical journals document the trends of recent decades but often these publications are not seen by conservators. PCN has published summaries of some developments and it is worth referring to a recent article in Pulp and Paper International by Dr. Ingemar Croon, a Swedish consultant. Dr. Croon has looked ahead a few decades and some of his expectations include the following. (Some of the comments below are mine rather than Dr. Croon's but the underlying forecasts are his.)

• Virtual replacement of chlorine bleaching by oxygen, hydrogen peroxide and ozone.
• A decline in the use of other chlorine compounds. Although chlorine dioxide may remain the main bleaching compound, particularly in Asia and South America, by 2010 most Scandinavian, Western European and North American mills will have shifted to the new technologies. By this time more pulp will be bleached with oxygen, ozone and hydrogen peroxide than with chlorine dioxide. Dr. Croon also mentions the benefits of chlorine dioxide in removing bacteria, fungi and phenolic residues. Since the latter degrade paper color, they must be of interest to conservators.
• A general decline in the quantities of chemicals used.
• More tightly closed water systems. This means that less water is abstracted from rivers and aquifers and less effluent is discharged. The down side could be an increase in chemical contaminants in the paper if they are not removed as solid or incinerated waste.
• More recycling of fiber, which may mean higher quality pulps are used as the virgin element. But what else may be recycled with the fiber?
• Greater use of secondary agricultural fibers such as straw and plants which can grow on set-aside or low grade land. These may include elephant grass and more exotic fibers. Since some of these have inherent problems such as high silica content, work on supplementary technologies such as desilication may expand.
• "Extensively-reformed" kraft pulping will be the dominant process over the next 10-20 years. Alcohol pulping and other special techniques will be rare although enzymes will have a role, possibly as a common state in more conventional techniques.

I would be inclined to believe that the majority of these changes will be benevolent in conservation terms but there may be several that are positively harmful. What is worrying is, that as far as I know, we have little idea of what the implications may be. Little research seems to be going on into the permanence implications and, as in many spheres, the production technology is evolving so fast that it is very hard to keep up with the side effects. These may be of great interest to us but they do not, generally, concern paper technologists, mill managers, financiers or environmentalists.

Is it not time to examine these issues? Otherwise we may find in 20 to 30 years that irrevocable damage is being wreaked by something as yet unrecognized.

As a start, can anyone who has knowledge of research into these areas contact IPC with details so that we may participate in building up a database? This may in turn suggest directions for research, and a summary of what is learned can be published by IPC from time to time.