acidity: an undesirable property in paste and mending tissue

Acidity: An Undesirable Property in Paste and Mending TissueAuthor(s): W. J. BarrowSource: The American Archivist, Vol. 30, No. 1 (Jan., 1967), pp. 190-193Published by: Society of American ArchivistsStable URL: http://www.jstor.org/stable/40290700 .

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190 TECHNICAL NOTES

Aperture Card Printer

A printer for automatically making low-cost paper copies from aperture cards has been introduced by 3M Co., St. Paul, Minn. Known as the "333" Dry Silver Printer, the unit will automatically produce up to 25 prints from each card without operator attention. The prints can be varied in size up to a maximum of i8"X24". Their cost varies according to size, with the largest costing about 9c each. The machine uses a new technology developed by 3M. It employs a dry silver paper that is developed by heat and light. Cleanup work is supposed to be minimal. Printing time depends upon the method of operation. Prints are produced at the rate of 3 per minute when manually operated, and 6 per minute when automatically operated. The paper comes in 500 and 1,000-ft. rolls, either 12 or 18 in. in width. The machine is about 5 ft. wide, 4 ft. high, and 2 ft. deep and weighs 350 lbs. It comes mounted on casters for easy moving.

Oral History Bulletin

Cornell University Libraries issued in July their first Bulletin of Cornell Program in Oral History. This newsletter is to appear semiannually and contain information about Cornell's oral history program. Included in the first 4-page issue are descriptions of the program's objectives, procedures, and current activities : All interviews are transcribed. Since it is important to preserve the flavor of first- hand conversation, these transcripts are as faithful as we can make them to the oral record. One copy is returned to the respondent for review along with a letter urging him to limit his alterations to changes which improve the accuracy or clarity of the transcript ("edit" has no place in our correspondence). Any changes he makes are transcribed to the other copies, one of which becomes his property. The third copy is placed in the Collection of Regional History at Cornell for the use of researchers. The respondent may retain literary rights in his interview. He may also restrict the use of his interview. Such restrictions are the price of candor. Only rarely does a respondent choose to restrict access to his interview beyond his lifetime. Most of the nearly 200 oral history transcripts at Cornell are available for use without the respondent's permission. We also preserve the oral record since some of the flavor of the interview is lost in even the most carefully prepared transcript.

A selection of current projects is described. They include interviews in such areas as labor management relations, Russia, Taft, Coolidge, Quantum Theory, progressive education, artificial breeding, Ithaca Festival, etc. The program's "principal concern is with persons less well known in their own time." Cornell expects to build an oral history collection of national significance.

Acidity: An Undesirable Property in Paste and Mending Tissue*

by W. J. Barrow

Barrow Research Laboratory

Paste and mending tissue are frequently used in archival agencies and libraries to make minor repairs on documents. These materials can easily be

* References are to numbered bibliographic entries found at the end of this paper.

THE AMERICAN ARCHIVIST



TECHNICAL NOTES 191 Table I

The hydrogen-ion concentration of active acids (expressed in logarithms - pH values) and their arithmetical equivalents follow.

pH A dive A cidity

3-5 3150

4.0 1000

4.5 320

5.0 100

. 5-5 32 6.0 10

6.5 3 7.0 1

obtained and used but may contribute to the long-range deterioration of documents that have lasting value.

The primary object of this report is to call attention to acidity, a deteriorative property often found in both paste and mending tissue. It does not discuss all materials and procedures that may be suitable or unsuitable for repairing paper.1'2 The findings stem from studies conducted under grants from the Council on Library Resources, Inc., which in turn is supported by the Ford Foundation.

As mentioned, acidity is a prevalent deteriorative property of both paste and mending tissue.1'2'3 Acidic compounds, carried by the water used in making paste, migrate back and forth between paste, tissue, and document. There does seem to be a tendency for acidic compounds to approach an equi- librium in some materials, but it is doubtful that such a state is ever fully achieved in repaired documents. "Repaired" documents, therefore, are not necessarily "saved" documents because the migration process may slowly con- tinue over a long period of time.4

The tissue used in mending documents of lasting value should be free of

injurious acidity. A pH 6.5 or above is desirable for good stability.5'6'7 For maximum longevity of documents, the presence of even a relatively small amount of acidity is undesirable. (See Table I.) For strength it is also desirable to have a long, strong, well-purified fiber tissue.

During the past year, this laboratory made pH tests on a number of domestic and foreign tissues that are used in repairing and laminating deteriorated documents. While most of the tissues showed satisfactory pH values, a few were found to be more acid than desirable.

Several restorers of documents recommended using an imported tissue and a domestic dried paste in repairing materials of lasting value. Laboratory tests on these two products showed that the tissue had a pH 5.4 and the paste a

pH 3.5. When these products (the paste having been made workable by the addition of 7 parts water by weight) were used in repairing a near neutral

paper (pH 6.7), the resultant laminate, or layered sheet, had a pH 5.6. While pH 5.6 is in the moderate acidity range, it is more acid than is desirable for a repaired document of lasting value.1«5

VOLUME 30, NUMBER I, JANUARY 1967



192 TECHNICAL NOTES

Table II The pH values of two tissues, three pastes, one unsized paper, and the combination

of all as a repaired document.

pH Values

« .; Tissue T' Dried Prepared Unsized Repaired Samples « .; Tissue T' D . * »..** n ± n ± Paste* D . * Paste** »..** Paper n ± Paper

n ±

1. Dried Paste 5.4 3.5 - 6.7 5.6 2. Dried Paste 7.1 3.5 - 6.7 5.8 3. Flour (bleached) paste 7.1 - 5.4 6.7 6.6 4. Flour (unbleached) paste 7.1 - 5.5 6.7 6.8

* One gram of dried paste was soaked in 70 cc. distilled water for 1 hour and pH (cold extraction) made of filtrate.

**The above procedure was followed but on the basis of one gram of solid matter per 70 cc. distilled water.

The paste used for repairing the paper was diluted (one gram of solids to seven of water), and efforts were made to apply about the same amount to each side of the sample before adding the tissue. All repaired paper was dried thoroughly before testing.

Since both products were acidic, the above paste was used to affix a near neutral tissue (pH 7.1) to both sides of the near neutral paper (pH 6.7). The resultant laminate had a pH 5.8. This value indicates that the paste alone contributes to an increase in the acidity of the repaired sheet and, therefore, creates an undesirable condition.

To explore the use of freshly made paste, both unbleached and bleached wheat flour were employed. The former was obtained from a small mill near Richmond, Va. Using either of these, a good workable paste was made from one part flour and two parts water by volume. Constant stirring and kneading with a wooden spoon prevented lumps from developing as the water was gradually added to the flour in a crock. The mixture was also stirred constantly while being cooked on a steam bath until it reached a soft, smooth consistency. Such a paste, it should be noted, must be made fresh daily in order to prevent spoilage (microbial decomposition) that makes it unfit for later use.

When the bleached wheat flour paste was further thinned by adding five parts water (near neutral) by weight and then used to paste down the afore- mentioned near neutral tissue and paper, the resultant laminate had a pH 6.6. The unbleached flour paste, when similarly thinned and used, produced a laminate with a pH 6.8. In other words, fresh paste made with either bleached or unbleached flour gave satisfactory pH values.

When thinned as above, the filtrate of the paste made from bleached flour showed a more acid (pH 5.4) condition than was anticipated. After standing overnight, the pH of this clear extract increased to 6.0 and, after being heated to 2OO° F. and cooled, the value rose to pH 6.8. These tests indicated the presence of volatile organic acids in the freshly made paste. The high volatility of these acidic compounds no doubt accounts for the near neutral laminate of samples 3 and 4 in Table II.

THE AMERICAN ARCHIVIST



TECHNICAL NOTES 193

Purchases of tissue intended for use in repairing documents of lasting value should be checked periodically by a competent chemist using the cold extraction method of the Technical Association of the Pulp and Paper Industry.5'7

Until thorough studies can be made of the various additives for improving the workability and the preservability of paste, it is a wise practice to make paste fresh daily, without additives, when repairing documents of lasting value.

BIBLIOGRAPHY

1. Barrow (W. J.) Research Laboratory. Permanence / Durability of the Book -

[/-/F.] Richmond, 1963-65. 2. Barrow, W. J. The Barrow Method of Restoring Deteriorated Documents. Rich-

mond, 1966. 3. Kantrowitz, M. S., E. W. Spencer, and R. H. Simmons. Permanence and Dur-

ability of Paper, an Annotated Bibliography of the Technical Literature From 1885 A.D. to IQ3Q A.D. Washington, 1940. (U.S. Government Printing Office, Division of Tests and Technical Control. Technical Bulletin, no. 22.)

4. Barrow, W. J. "Migration of Impurities in Paper." Archivum, 3:105-108. 1953. 5. Barrow, W. J. "Hot vs. Cold Extraction Methods for Making a pH Determination."

Tappi, 46:468-472, August 1963. 6. Clapp, Verner W. "Permanent/Durable Book Papers." ALA Bulletin, 57:847-

852 (Oct. 1963). 7. Technical Association of the Pulp and Paper Industry. Hydrogen Ion Con-

centration (pH) of Paper Extracts. Oct. 1952 (T 435111-52).

Ml AMERICANA IN MICROFORM

A series of micro-reproductions of British Records Relating to America. Selected by the British Association for American Studies under the general editorship of Professor

W. E. Minchinton of the University of Exeter.

The Papers of the American Unitarians. One microfilm reel of the corre-

spondence of Jonathan Mayhew, John Gordon, etc., from the Unitarian College, Man-

chester. Edited by B. W. Clapp of the University of Exeter, and F. Kenworthy,

Principal of the Unitarian College.

The Owen Papers. The American correspondence of Robert Owen 1821-1858.

Filmed from the material in the library of the Co-operative Union, Manchester. Edited

by Peter D'A. Jones of Smith College, Massachusetts.

The Pocock Logs. The journals of Nicholas Pocock, R.A., Master of the Ship Lloyd, 1767-1772. These are four journals of voyages between Bristol, South Carolina, Dominica, and the West Indies.

Complete listings, with brief descriptions of the contents of each archival holding, from:

MICRO METHODS LIMITED East Ardsley, Wakefield, Yorkshire, England.

VOLUME 30, NUMBER I, JANUARY 1967

