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[BKARTS] Dating prints: correlating age and wear

S. Blair Hedges, a biologist based at Penn State, has recently published an article in the ?Proceedings of the Royal Society? (21 June 2006) in which he presents a method for dating early books and prints using image analysis; and his article has been mentioned on various Book_Arts-L and ExLibris postings. For a popular account of Professor Hedges?s work, see Emily Anthes? 7 July 2006 account in Seedmagazine.com:


Hedges deals with both relief and intaglio printing of the hand-press period. His theories are based on the examination of the successive editions of only three books, and ? though some parts of his methodology may eventually prove to be of some use when used with larger samples and taking other kinds of evidence into account ? his current conclusions cannot be not be taken very seriously.

It is a general assumption, Hedges states (citing Hind, McKerrow, Gaskell, and Griffiths), ?that deterioration of woodblocks and copperplates occurred from use,? but he claims that the true cause of deterioration is time, not use: the wear takes place *between* editions rather than *during* the printing of these editions.

Wood block printing
The technique of using wear to date wood-block prints is well?known. Hedges suggests that the deterioration of wood blocks is time-dependent, rather than print-dependent ? that is, that wood blocks tend to deteriorate more as the result of their age than as the result of the number of times they were printed or the circumstances of that printing. His conclusions are based on the examination of the three c16 editions (1528, 1534, and 1547) of a single book, Bordone?s ?Isolario?; he correlates the progressive deterioration of the blocks over these three editions with their publication dates, finding increasing signs of wear from one edition to the next.

Wood blocks do indeed wear very little as the result of the actual printing process, though they will wear and develop damage during the process of cleaning them (by scrubbing) at the end of the day?s press run. Improperly stored, wood blocks can develop cracks and otherwise deteriorate over long periods of time, and there may be some correlation between the age of a block and the evident deterioration of prints produced from it ? but many other factors need to be taken into account (including climate, storage conditions, and the number of impressions within in an edition) before it would be possible to posit a simple correlation between time and wear.

Copperplate printing
Hedges? conclusions are based on his examination of various editions of only two c16/early c17 books, Porcacchi?s ?L?isole piu famose del mondo? and Magini?s ?Geographiae.? He estimates the number of copies originally printed according to the number of surviving copies he has been able to locate in online and printed catalog sources (a dangerous methodology), and he assumes a constant number of books printed for each edition (a dangerous assumption). He finds that the plates deteriorate over time, resulting in fainter images, and that the deterioration is caused by the erosion of the surface of the copper plate.
?It is widely held [he states, citing Hind, Verner, and Griffiths] that deterioration of copperplates is the result of the printing process itself, and, in particular, the great pressure of the rolling printing press? and that ?such a mechanism predicts that copperplates are compressed over their lifespan, and that lines become wider.?
Hedges has misread his sources: what is widely (indeed, so far as I am aware, universally) held elsewhere is that the heavy pressure of the rolling press has an ironing-out effect on copper plates, *narrowing* the engraved and etched lines which thus become less capable of holding ink and which thus print lighter (and eventually broken) lines.
Hedges suggests that the later impressions become lighter because of the erosion of the surface of the copper plate between print runs, and the necessity of grinding and polishing the surface of the plate before another printing can take place. The longer the period of storage, the greater the surface corrosion and the greater the amount of polishing necessary to remove it ? and thus the greater amount of wear.
We have little evidence regarding the storage of copper plates over long periods during the earlier part of the hand-press period. To use age as a sole predictor of wear ignores the importance of storage and climate conditions, the skill of the rolling-press printer and the copper plate refurbisher, and the frequency with which a copper plate was used. The story is quite different for engravings used in books (where the runs would be long) as opposed to engraved maps and single-sheet engravings intended for framing (where the individual runs would tend to be quite short, though cumulatively they could be quite long). Hedges provides insufficient evidence to posit that copper plates wear primarily as the result of the polishing process that may occur between runs separated by longish periods of time, and he ignores a great deal of evidence both ancient and modern showing that copper plates wear significantly -- and primarily -- during the course of a single press-run.

Hedges cites a recent article by Karen L. Bowen and Dirk Imhof that appeared in vol 22/no 3 (2005) of ?Print Quarterly.? He notes:

The recent discovery that a single copperplate was used to print as many as 18 000 prints (up to 6400 without retouching; Bowen & Imhof 2005) compared with previous estimates of 1-3000 prints per plate (Hind 1923) supports the hypothesis here that most plate deterioration was probably not from the action of printing. (p. 17)

The article uses Plantin-Moretus printing records to show that the engraved copper-plate frame used for the title pages of various volumes (and editions) of Caesar Baronius? ?Annales ecclesiastici? published between 1601 and 1658 survived through eight or more reworkings to produce more than 18,000 copies. The Bowen/Imhof article?s conclusions are fascinating and revelatory. It is not possible from the small-sized illustrations accompanying their article to assess the effect of the copper-plate title page frame?s wear on the images produced (though the deterioration was clearly very considerable). Most scholars will wish to see evidence of additional instances drawn from printing records, Plantinian or otherwise, before they are willing to change their thinking about the number of copper engravings typically capable of being produced from a single plate, especially for up-market work.

Terry Belanger
University Professor, Honorary Curator of Special Collections
Director, Rare Book School : University of Virginia
Rare Book School : PO 400103 : Charlottesville, VA 22904-4103
Email belanger@xxxxxxxxxxxx : Phone 434-924-8851 : Fax 434-924-8824
URL <http://www.rarebookschool.org>

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