Acid paper

S. Arrington and G. Bradley, "Service Water System Cleaning with Ammoniated Citric Acid," paper presented at Corrosion 87-NACE, No. 387, San Francisco, Calif., 1987. 

Why does the amount of acid in paper make such a difference Acids are corrosive chemicals. Corrosive chemicals can destroy material or living tissue on contact. Paper does not contain enough acid to burn skin, but over time the paper becomes stiff and brittle and eventually falls apart. As a result, precious personal memories or important historical documents that were written on acidic paper can be lost. Acid-containing paper can also transfer the acid to other objects in a process called acid migration. The acid can weaken or destroy the fibers in fabrics. It can also ruin photographs. Therefore, to preserve those irreplaceable memories, be sure to use paper that is acid-free. 

Acidic ion-exchange resins, 10 485 Acidic oxides, 12 190-191 Acidic papers, preservation of, 11 414 Acidic properties, of titania-silica, 1 764 Acidic silicate solutions, 22 458 Acidic zeolites, 16 825 Acid industrial refractories, 21 515 Acidity, biofiltration system, 10 76-77 Acidity analysis, of water, 26 36-37... 

Figure 10.17 Two-dimensional high voltage electrophoresis and chromatography of amino acids. Paper high voltage electrophoresis (4000 V) in an acetic acid-formic acid buffer at pH 2.0 in the first dimension followed by descending chromatography in the second dimension in an n-butanol-acetic acid-water solvent (12 3 5). The spots were visualized with a ninhydrin-collidine reagent.

Miller, D. F., and C. W. Spicer. A Continuous Analyzer for Detecting Nitric Acid. Paper 74-17, Presented at 67th Annual Meeting of the Air Pollution Control Association, Denver, Colorado, June 1974. 

Amino acid paper electrophoresis has sufficient sensitivity and reproducibihty for amino acid analysis. If analysis by HPLC is not available in or around your lab, paper electrophoresis may be an alternative. 

Originally, Edman hydrolyzed the PTH-amino acids and identified the free amino acids by paper chromatography 0. Since not all of the amino acids are sufficiently resistant to this treatment Edman and Soquist subsequently devised methods for the direct identification of the PTH-amino acids. Paper chromatography has now generally been abandoned in favour of the more sensitive thin layer chromatography Recently, gas-liquid chromatography... 

See Perchloric acid Paper, Silver compounds See Zinc Sodium hydroxide (reference 3)... 

Since its initial application to the separation of amino acids, paper chromatography has been widely applied to the separation of many classes of compounds, including peptides, organic acids, inorganic ions, antibiotics, steroids, and amines.7 A number of monographs on paper chromatography are available.8... 

However, much can be done to minimize damage caused on the shelves or by library users if the material is stored in acid-free folders. They are easily fabricated and many types suitable for archive use are available commercially. It is essential that clearly acid papers be stored separately from nonacid ones in order to prevent migration of the acid. Some conservators place a sheet of buffered paper in the folder to absorb free acid from the print. 

The paper machine came into use around 1830. Before, paper had been sized in a separate operation with gelatine or glue. Now a new size was introduced, rosin and alum, which could be added to the beaten stock. The paper then came from the machine in the sized condition. The amount of alum required for sizing left the paper acid. This was the final blow to permanence. Acid paper does not last well it quickly turns brown and brittle. The life of paper which under good conditions could be 2000 years now was reduced to around 75 years. 

There is a striking difference, however, in the action of various alkaline materials. Neutralizing acid paper with sodium carbonate, as is shown later, prolongs its life. Alkalizing paper to pH 10 with sodium carbonate causes paper to darken, to oxidize, and to degrade. The effects are most pronounced in humid-oven accelerated aging, less so in the dry-oven aging. 

Barrow, who was developing cellulose acetate lamination as a method of preserving documents, took the step of applying the bicarbonate solutions to the preservation of acid papers, both those still with adequate strength and those weak and requiring lamination. According to Clapp... 

TAPPI method T-453-ts-63, which uses only the dry oven, gives a satisfactory estimate of the stability of acid paper but has no value in predicting oxidative degradation or the life of a paper containing the oxidation catalysts. The humid oven will find both acid degradation and oxidative degradation. 

Douren, L., Sandvik SX—The Future Material for Concentrated Sulfuric Acid, paper read at Sulphur 87, Houston, TX, Apr. 5-8, 1987. 

Symposia, such as the one reported in this volume, give scientists and conservators the opportunity to meet and communicate. Scientists need to be educated in the problems facing conservators. Conservators should learn where science can assist and where it cannot. The problems of conservation can be quite difficult and may take years to solve or may be unsolvable. The permanence of paper dropped abysmally, starting around 1850. The reasons for this drop were researched for one hundred years before the answers were found. Another several years passed before it was demonstrated that sized permanent paper could indeed be made on the paper machine. Permanent paper can actually be manufactured more economically than the impermanent variety. There is less attack on the machinery of the plant, and the plant effluent is cleaner. Yet papermakers continue to produce the inferior product. Our libraries and archives must still accept short-lived acid paper to add to their already overflowing collections of brittle books. 

Figure 7. Change in aging rate attributable to morpholine-water vapor treatment of an acid paper (O), treated, (+) untreated (12)...

A much more recent development is the morpholine process in which fifty books per hour are treated in an evacuated chamber with morpholine-water vapor (12). In its present form, it was effective on 95% of the papers treated, prolonging their life on average by a factor of 4-5 (Figure 7). Though it does not leave a titratable alkaline reserve in the paper, acid papers treated in this manner aged in the presence of 5 ppm S02 at 75 °C and 60% relative humidity deteriorate more slowly than if untreated. Recent tests of twenty treated books at the Library of Congress show that their pH has not declined in two years. The equipment for the process was set up in the Virginia State Library where 35,000 books were treated in the first seven months of operation. 

It is not difficult to guess why the time-ratios in Figure 3 increase as degradation proceeds. The cold extraction pH of the acidic paper was found to decrease during the degradation process, reaching pH 3.8 by the end of the experiment. The pH of the buffered paper remained constant. Therefore, it seems probable that the increased value of the time-ratio as degradation occurred is a manifestation of an autocatalytic process. Similar results were obtained in the comparison of samples of a buffered and a not-buffered rag paper. Thus, the autocatalysis process... 

T veacidification plus the incorporation of an alkaline reserve greatly extends the life of acid paper. However, the treatment does not restore the pliability and folding endurance that have been lost. There is a need for a method that will regenerate these properties. This should be ultimately a mass method and should preferably be carried out in conjunction with one of the mass deacidification treatments presently being developed. 

As acid paper ages, the amorphous regions of the cellulose fiber that are plasticized by water and/or humectant tend to disappear. The sorbi-tol/Kymene treatment becomes ineffective with degraded paper. This suggests that somewhat the same effect would be observed between new and degraded papers when humidified. Adrian Sclawy of the Library of Congress Preservation Research and Testing Office, carried out the experiments on humidification which are reported in Chapter 16 of this volume. 

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