Wednesday, September 24, 2008

Effects of Historical Inking Technologies

The Image Permanence Institute (IPI) defines archival as “A term often used to imply that a material will be stable over time. The term has neither a recognized standard definition nor a quantifiable method for verification.” There are many aspects as to catalysts for the permanence of a paper most of which is determined by how the paper was made, also known as pulping or papermaking. Depending on the process of the pulping and paper-making, this could determine the length of time that a piece of paper will be able to stay as a stable object and this stability can also be affected by the printing that is done onto the paper: whether it is ink or the use of a pencil.

According to the Library of Congress Pub. L. 101-423 (Appendix 1):
Definition of permanence
Pub. L. 101-423 (Appendix 1) recommends the use of "acid free permanent paper" using the specifications established by the Joint Committee on Printing (JCP). For purposes of clarity, this report adheres to the JCP specifications. Thus, an acid free permanent paper is defined to be:
* A fully bleached sheet with a pH of 7.5 or above,
* An alkaline reserve of 2 percent or more,
* A minimum MIT folding endurance in either direction of 30 double folds, and
* A minimum tearing strength in either direction of 25 grams for a 30 lb paper
and proportionately higher tearing strengths for heavier papers.

This definition matches most closely the first specification for permanent paper, ANSI Z39.48-1984, developed by National Information Standards Organization, which has strong support in the archival and library communities. (LOC website1)

Permanent is biased term in this industry because nothing is permanent, but it means that the object being showcased as “permanent” means that it has an extended life beyond that of a normal sheet of paper that you would purchase from an office store in a ream of 500 sheets. For all government documents, the Library of Congress has been given authority to demand that all documents are to be printed on “archival” paper. Not only does the method to the papermaking process affect the life expectancy of paper, but the method of writing and type of ink on the paper will also affect the longevity of the paper.

There are four different pulping processes: chemical, mechanical, semi-chemical and thermo-mechanical pulping. Mechanical pulping is defined as the process that produces ground wood pulp. This is the most economical process since all the wood is used, but it does contain impurities that contribute to the discoloration and weakening of the paper. Old, yellow newsprint is an example of this process (PP182). Chemical pulping is defined as the process that removes most of the impurities from the elements of the wood that contribute to the discoloration and weakening of the paper such as lignin, resins and gums (PP182). By removing these impurities it leaves only the cellulose fibers, which promotes permanence by riding the paper of components that fade and yellow the paper. Within the chemical pulping process there are two types of the chemical pulp. The first named as Sulfite pulp is made from cooking the wood chips from coniferous trees in a mixture of lime and sulfurous acid (PP182). Since an acid is used to create this, it weakens the paper. The second type named as Sulfate pulp, which uses a variety of pulp, which inherently creates a stronger paper, thus making sulfate pulp the more widely used of the pulp in the chemical pulping process (PP182). The third of the four pulping processes is known as Semi-chemical pulping (CTMP). This process combines the first two processes together to form a pulp that produces a higher yield, but is similar to chemical pulping. This means that this process uses the majority of the wood that is ground into pulp, as in mechanical pulping, but some impurities are also flushed out as in the process of the chemical pulping process. The blend of the pulping processes produces a paper that has similar qualities of the end products of chemical pulping such as stiffness and good formation with the economical cost of mechanical pulping. The last of the four pulping processes is known as Thermo-mechanical pulping (TMP). This process uses heat to refine the wood chips that are used to make the pulp. By refining the wood in this process, you achieve a higher yield with a moderate price and it is strong enough for newsprint, but it still does not produce a permanent solution. Thus stating that to produce papers specifically for permanence, one would need to use the chemical pulping process or the semi-chemical pulping process. The chemical pulping process will produce paper that has an undefined life span.

The chemical pulping process produces a paper known as “Alkaline Paper”. This is paper that is also known as “acid-free”. After the chemical pulping process occurs, all that is left are the cellulose fibers from the wood. Fibers made of cellulose chains degrade when exposed to an acidic environment in the presence of moisture. In this acid hydrolysis reaction, cellulose chains are repeatedly split into smaller fragments so long as the source of acid remains in paper. This acid hydrolysis reaction produces more acid in the process, and the degradation accelerates in a downward spiral (LOC website 2). If these cellulose chains are longer then the paper will be able to withstand more pressures such as environmental changes, handling and temperature/humidity changes. When papers are recycled, this is when the fibers are shortened therefore weakening the paper and causing it to not be able to withstand the environmental changes. Alkaline papers are comparable to cotton papers, which is one of the oldest papermaking methods and because cotton fibers are naturally very long it will naturally prolong the life of the paper, indefinitely. There are issues to the alkaline papers such as the acid that the cellulose fibers naturally produce. Cellulose itself generates several acids, such as formic, acetic, lactic, and oxalic acids. Measurable quantities of these acids were observed to form within weeks of the manufacture of paper while stored under ambient conditions. This research also shows that these acids continue to accumulate within paper as they attach themselves to paper through strong intermolecular bonds. This explains why acid-free (pH neutral) papers also become increasingly acidic as they age. Acids are formed even in alkaline paper, although in this case they are probably neutralized by the alkaline reserve before they can do any damage to the cellulose molecule (LOC website 2). Since papers create their own acids, there is a problem with storing books. Since the pages of books are more compactly squeezed together this promotes the degradation of the paper because the pages are closely together with no air in between pages to help rid the pages of the acids. To help prevent the degrading of books, they are generally placed into cold storage facilities or the library initiates a mass deacidification process, which can extend the life of the materials by twice or three times the typical life expectancy.

Through my research I have come to realize that the acids making up the composition in ink is a more complex process than someone of my background could develop. Since studying at the Rochester Institute of Technology, I have been exposed a few times to the Image Permanence Institute (IPI) and so I enlisted in the help of the IPI in order to receive more information about the composition of some of the more acidic inks dating back through history. This help was obtained through an e-mail interview with Douglas W. Nishimura from the Image Permanence Institute. "Probably the obvious example of ink causing paper deterioration is the case of iron-gall ink. It was the standard ink used in Europe from the twelfth century through the nineteenth and even into the twentieth century. The stuff was relatively cheap and was made by mixing an iron salt, typically ferrous sulfate with the tannin extracted by boiling oak galls (galls are rather knobby lesions that form on the tree as a result of viruses, bacteria, fungi, nematodes, physical injury, and especially insects. These things are so round that they were often called "gall-apples". Anyway, if you boiled them up and added a ferrous salt (Iron(II)) salt) to the solution, you got a pale grey solution that darkened to a deep purple-black. It adhered well to vellum and paper and at its best; it formed a very readable high-contrast ink. It has even been used as a "photographic" process. Paper is first treated with a combination of gall tannin and a light-sensitive iron salt such as ferric ammonium citrate. (Notice that the iron is in the ferric (+3) state). Upon exposure to light, the ferric salt is reduced to the ferrous state and the ferrous salt reacts with the tannin to form the dark ferrogallate. The problem with this process and the ink is that the ink is very acidic and attacks the paper,” says Nishimura. This ink was used for so long and so often because it was inexpensive to formulate and was very permanent. Another ink that was being used during the late middle Ages was carbon ink, but it was not preferable to iron-gall inks because the "carbons inks could easily smudge with high humidity and was easy to remove from a document" (ICW). Iron-gall inks were also superior to carbon inks because iron-gall ink was easier to manufacture, would not clog the writing tool, and was difficult to remove from the surface where it had been applied, which is a valued characteristic for official record keeping.

Demonstration of Pencil on Paper and how it does not penetrate the fibers (top)

Demonstration of Pen on Paper and how it does penetrate the fibers (bottom)

Photos by Emily Bair on the Zeiss Axioskop2 with the AxioCam HRc 10x


Nishimura, Douglas W. E-mail interview. 28 Apr. 2008.

Image Permanence Institute (IPI)
"Glossary." Image Permanence Institute (IPI). 2007. Rochester Institute of Technology. 6 May 2008 shtml_sub/glossary.asp.

Library of Congress (LOC) website 1
"Definition of permanence." Library of Congress Preservation. 18 Oct. 2006. Library of Congress.
18 Apr. 2008

Library of Congress (LOC) website 2
"The Deterioration and Preservation of Paper: Some Essential Facts." Library of Congress Preservation.
18 Oct. 2006. Library of Congress. 6 May 2008

Pocket Pal (PP)
"Paper." Pocket Pal: the handy little book of graphic arts production. 1934. Ed. Frank Romano and
Michael Riordan. Nineteenth ed. Twenty vols. Memphis, TN: International Paper Company, 1934,
2003. 181-201.

The Ink Corrosion Website (ICW)
Eusman, Elmer, and Birgit Rei├čland. "Iron Gall Ink." The Ink Corrosion Website. 2006.
European Commission on Preservation and Access in Amsterdam.
6 May 2008