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2. Water-soaked paper
2.1 Associated problems
2.1.1 Absorption and swelling
Paper has a normal hydroscopic capacity for absorbing water. However, paper made before the middle of the nineteenth century has an even greater capacity for the absorption of water thanks to the greater amount of water-soluble sizing used in that early period. For example, books of this period will absorb up to an average of 80 percent of their original weight. Furthermore, paper of this period used for books or manuscripts is highly vulnerable to microbiological infection. However, such paper will survive total immersion in water for longer periods than paper made after the mid-nineteenth century. Books made after this time were treated with water-resisting sizes; they absorb an average of 60 percent of their weight. So, in estimating the original weight of a collection, if each book weighs about four pounds (1.81 kilograms) when dry and there are, for example, about 20,000 of each period, one must plan for the removal of 64,000 pounds (29,000 kilograms) of water from the earlier period and 48,000 pounds (21,773 kilograms) from the later (5).
As to swelling of books, the mayor part of damage takes place within the first eight hours after soaking.And since the text block and book covers swell more than the covering material, the tensions produced causes the spine to become concave and the fore-edge convex. The straining forces the case of the book to become partially or completely detached (5).
2.1.2 Microbiological infection
Gallo (6) describes a number of schizomycetes (bacterial) actually low in number, and about 100 species of fungi which, under favorable conditions, attack and infest the organic matter in paper. Although the spores of the fungi and the schizomyceti are present in the raw materials used for the manufacturing of paper waiting for conditions favorable for development, the infection of documents is more attributable to the spores ever present in the air or dust. Spores Deed air to develop; a book or a bundle of manuscripts totally immersed in water are immune from attack. And since the spores of the fungi cause more frequent and greater damage than bacteria, this study will focus on the former.
The microbial spores of the fungal plant, of which the most common is called mold, need the following elements in order to reproduce: humidity, a relatively warm temperature, and a nutrient. The first, humidity, is present in abundance when water floods an archives or library. And a temperature higher than normal is present if the season is warm (the problem is less acute if it is cold), if ventilation is poor, if the air conditioning system breaks down, or if there is heat present generated by an extinguished fire. The third element, the nutrient, is essential because the fungal plant, which has no chlorophyll to convert carbon dioxide to carbohydrates for tissue growth, must get its carbohydrates directly from organic matter. Unfortunately, there is plenty of nutrition available in the cellulose of paper, the protein in parchment and leather, along with the nutrients in animal and starch adhesives used to size, glue and paste.
Kowalik (7) adds that microorganisms not only have cellulose at their disposition but also other substances such as lignin, hemicelluloses, pectins, waxes, tannin, and mineral constituents. Furthermore, paper may contain resinous fillers, dyestuffs, added during the productive cycles, and various impurities which may also form a part of the microbial diet.
In any case, if the temperature is in the 18° to 36°C (65° to 96.8 °F) range and the relative humidity above 65 percent, chances are that mold infection will appear on wetted books and documents in about 72 hours after flooding takes place This, however, is not a hard and fast rule. Waters (8) reports a case where mold developed rampantly on the water-soaked spines of rare books to a thickness of 1/4 to 1/2 inch (6 to 12.7 millimeters) some 52 hours from the onset of a disaster. As a matter of fact, during long-term storage fungi will grow, although slowly, at a relative humidity as low as 60 percent. And recently the National Library of Wales (9) experienced mold infection (no flood involved) on a number of items where the relative humidity was not only well below 70 precept, but in some cases as low as 50 percent.
The first visible evidence of mold infection is a white powdery mass that will appear on the surface of a document or a book. Sometimes you need a raking light to detect it. Even a slight trace is a warning that temperature and humidity are above the limits for safety. At this point, the fungal plant has grown hyphae (root-like organs) into the stratum of the nutrient in order to get food for its development. as the plant metabolizes the substances required for its growth, it secretes citric, oxalic, lactic, and other organic acids which damage the material on which the mold is feeding. At the same time, the plant secretes pigments of green, blue, brown, black, red, and yellow color which are deposited on the host. These stains are practically impossible to remove; they can obliterate the text of a manuscript or book.
When mold attacks paper other complex things happen: the strength supplied by the sizing in paper diminishes; when cellulose suffers the attack, the structure of the paper is damaged to the point that it will become soft or so fragile that it will actually break.
Gallo (6) points out that in some cases fungi can exercise a mechanical action on paper: their hyphae may filtrate between fibers of the paper without actually entering them, or the fruit bodies of the fungi, which are covered with bristles, infiltrate between one feat and another; in both cases the pages of a book or documents in a bundle are welded together.
2.1.3 Adhesion of leaves
When a bundle of documents or a book has been soaked and permitted to dry under favorable conditions, it will begin to lose its water content from the outside surface. Capillary action permits the interior water to move outward and carry with it all varieties of water-soluble materials such as dyes, pigments, adhesives, and acids. In a book, the concentration of these materials, the acids and adhesives in particular, will cause the edges of the text block to become embrittled and edges stick together. Ii these text blocks are left in this condition after drying, serious degradation of the cellulose in the paper will be speeded up (8).
Books on coated paper present special problems. Coatings are usually applied to paper in order to obtain uniformity of surface, to enhance opacity, smoothness, and gloss. The basic components of coatings contain pigments such as China clay or a solubilized protein (10). Waters (8) notes that in the presence of water, starch-based coatings and some casein mixtures may revert from dry adhesive to gel and then back to the solid on drying. When these adhesive mixtures are in a fluid state, any pressure will cause the coatings to weld together and create a permanent bond during the drying cycle.
2.1.4 Migration of inks and dyes
In case of wetted hand-written documents or bound volumes where inks have been used, the archivist and librarian face the problem of feathering or migration of those inks. In the two principal categories of inks, those made from carbon pose no problem since this organic material is not soluble: its binding medium (glue or gum), even when long decayed, leaves the carbon particles embedded in the paper fibers. However, there are inks that may look like carbon but are, in fact, quite soluble. In the second principal category are the so-called iron inks which are compounded from gallotannic acid in the presence of iron in a binding medium. Where carbon remains on the surface, iron inks soak into the paper so that the insoluble iron compounds formed when the ink matures are held as an integral part of the paper surface. In those cases where mature iron inks become a rusty brown or yellowish color it is not safe to assume that all inks of these tones are of iron and therefore insoluble. These same colors can appear with inks made of sepia or beechwood root which are impermanent (11)
Through all times inks have been made according to a multitude of recipes, and as a result vary in substance, appearance, and permanence. Some more modern inks are made "permanent" for fountain pens by using iron sulphate and tannic acid. However, the dyes used for toning will feather in water. Some inks used for writing have little more than a dilute aqueous solution of one or more synthetic dyestuffs. Other "permanent'' inks like those made of iron compounds will run or feather in water until they are matured or, said in another manner, properly oxidized. As for colored inks, most of them are soluble with or without aging.
While most holdings in archives and libraries are of non colored paper, the majority of the more modern material, even if it appears to be white, contains coloring matter added to improve appearance. For toning or coloring there are two mayor classes of colorants used: colored pigments and water soluble dyes. Of these the latter are the most used. The word ''soluble" means that a dye is soluble in water and colors the fibers from a solution in water. Such colors are impermanent and will run when wetted
The problems associated with water damage to archival and library materials - absorption and swelling, mold infection, blocking or adherence of leaves, migration of inks and dyes get worse with the passage of time; salvage becomes more difficult, costs may go up. Future repairs and restoration may become more complicated, more expensive and time consuming. In short, time is a problem if it is not available. However, there is a way to by an unlimited amount: you do it with a process called stabilization by freezing.
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