USGS Printing Techniques
In a previous post, I noted the need to reassess one’s assumptions. Here’s an instance in which my assumptions were challenged, but in the end held up.
The issue is this. During my visit last July to the Rare Books School at the University of Virginia, I met Amira Hegazy, an artist and printer, who’s been working as a collections assistant at RBS. She was interested in knowing more about how the US Geological Survey printed from its copper plates, and in doing so she led me to question my assumptions about how the USGS treated its plates.
USGS Copper Plate Topographical Maps
Ms Hegazy was referring to the USGS’s “topographical quadrangles” at 1:62,500, which it began to produce in the 1880s, each covering 15 minutes of latitude and longitude (thus “quadrangles”). Each of these images feature three colors, so three printing plates: brown for height contours; blue for water features; black for “cultural features” such as boundaries, human settlements, and toponyms.
It is very difficult to get anything like a good photograph of these polished copper plates, so I’m cheating and using images from a USGS pamphlet:
In the nineteenth century, all the official mapping agencies in Europe still used copper plates for engraving their topographical maps, just like their lineal predecessors in the eighteenth century. The USGS followed suit when Henry Gannett set up its Topographic Branch in 1884 (Evans and Frye 2009, 24–25). But unlike the Europeans, the Americans adopted contours to show relief, not the hachures long preferred by military strategists and tacticians, and they printed in color. (By comparison, in the United Kingdom, the Ordnance Survey adopted contours and color printing for the “Third Series” of the equivalent 1:63,360 maps in 1898). The USGS stopped updating and printing from the plates only after WW2, as it slowly replaced the 1:62,500, 15' quadrangles with more detailed work: 7.5' quadrangles at 1:24,000. (The new series was prepared through new, photomechanical processes.)
The USGS has slowly divested itself of the heavy, cumbersome copper plates. (Each plate is 17" by 21" and weighs 12.5lbs.) Eventually, in 2014, with nearly 4,000 sets of plates remaining (each set comprising the three plates), the USGS began to offer the plates to cultural institutions. Then, in 2015, it set up a public online auction, by which it sold off 2,262 plate sets.
Copper is soft, even the harder alloys used for the USGS plates, so that the USGS did not print the final maps directly from the copper plates. Rather, right from the start (Phillips 1997, 12), the image of each plate was transferred to a lithographic stone for mass printing. The USGS later prepared separate layers for woodlands (green) and main roads (red) directly on lithographic stones (or from zinc plates).
How was the transfer from plate to stone achieved? My assumption was that they simply pulled an impression and, when the ink was still wet, transferred the image to the stone.
Ms Hegazy caused me to question this assumption. One set of plates in the public auction was acquired by a resident of the same town in which Ms Hegazy lives, and he asked her to print them. The effort was substantial: the plates were heavy and warped; after inking, it took for ever to clean the excess ink off the surface of the plates; and it took very delicate and careful press work to get an impression. It was very difficult to get the different colors to register (align) precisely. She was nonetheless able to successfully print several copies of the map in three colors.
But her difficulties made me wonder whether the plates were actually meant to be printed and if some other method was used, such as some kind of electrotyping or another arcane nineteenth-century technology, to transfer the engraved image to the lithographic stones. I decided to double check my assumption, which has been possible thanks to the wonders of the Internet.
Early in the twentieth century, the USGS’s chief engraver, Stephen J. Kübel gave a brief overview of the processes used in the Division of Engraving and Printing:
After the engraving of the copperplate has been completed the work is transferred to stone and printed by the usual means on power presses. (Kübel 1908, 77)
Two decades later, a more extensive discussion of the engraving and proofing process, began unpropitiously:
Transfers are afterward made from the three copper plates to three lithographic stones, from which the maps are printed. (Beamon 1928, 336)
However, as the account continued, further information was adduced about the treatment of the plates. In terms of the proofing process, we find:
First plate proofs.—On the completion of the engraving on the three copper plates “first plate proofs,” in black, are pulled from each of the three plates, are inclosed in the jacket together with the original map and all engraving copy, and are referred from the engraving division to the section of inspection and editing for revision. (Beamon 1928, 337)
Hmmm: the plates were indeed printed. The process of transferring the printed image remained so ordinary as to be unspecified:
Combined proofs.—When the corrections called for in the reading of the second plate proofs and the letter check have been made on the three copper plates, transfers are made from each plate to three lithographic stones, and to these stones are also separately transferred from type impressions or from stock engravings such lettering, notes, scales, etc., as may not be engraved separately for each map. From these three stones, representing the culture, relief, and drainage features of the map, are printed combined proofs in the colors to be used on the published map. (Beamon 1928, 339)
At this point, reference should be made to modern technical manuals concerning the transfer of (any) images to lithographic stones, as:
The transfer was produced similarly to any intaglio print, the major exception being that an especially greasy ink and special transfer paper was used …, especially treated … with a gelatine-like coating … After [the impression was made], the transfer paper was placed face down on a lithographic stone, then the two were passed under the scraper of a lithographic press. The paper was dampened and then could be pulled away leaving the transfer ink and the gelatine on the stone like a decal. The gelatine could be dissolved from the stone with additional water. (Phillips 1997, 15)
So, it looks as though assumptions can be correct!
Coda: Getting the Surveyors’ Work to the Copper Plate
There was one odd and typically complex nineteenth-century process in use that was quite new to me, specifically the method developed by USGS staff to transfer the compilations of surveyors’ work to the copper plates in the first place. The original method was probably the traditional manner of covering the plate in thin layers of wax and charcoal, laying the drawing face-down, and then tracing all the lines from behind; pressing down on the drawing mixed charcoal with wax and fixed the image so that it could then be engraved (the engraver’s burin cutting through the wax and into the copper). Other techniques steadily developed to make this process easier, faster, and more accurate (Phillips 1997, 13–14):
An interesting process is employed to transfer the design from the copy to the copperplate—a process which has been developed in the engraving division and which has proved to be of great practical value in securing accurate and economical results. It is not possible to give a satisfactory written description of this process, but it can be stated that it is a combination of zinc etching, rolling up by wax, transferring to copperplate, and staining of the plate by fuming or by immersion in a staining solution. This is, perhaps, the only process employed here that may be called unusual, all others being about the same as those in common use. (Kübel 1908, 77)
The later Topographical Instructions gave a fuller account of a somewhat different process employed twenty years later:
Engraving.—A polyconic projection is constructed on each of the three copper plates on the scale of the map publication. The original drawing of one map that is to be engraved is photographed to the publication scale, and from the glass negative a contact print is made on a zinc plate, on which the map features are in the reverse positions to those on the original drawing. The map on zinc is transferred in turn to each of the three copper plates by means of wax impressions obtained on celluloid and burnished down on the copper plates, where the impressions are suitably fixed. Transfers to the copper plates are made in small sections at a time, usually by coordinate blocks, in order to distribute any small errors that may exist in the scale of the original map. The reproduction of the map that has thus been transferred to copper is reversed, and the engraver must do his work in that position. (Beamon 1928, 337)
Beamon, W. M. 1928. “Topographic Mapping.” In Topographic Instructions of the United States Geological Survey, edited by Claude Hale Birdseye, 161–378. USGS Bulletin, 788. Washington, D.C: G.P.O.
Evans, Richard T., and Helen M. Frye. 2009. History of the Topographic Branch (Division). USGS Circular, 1341. Reston, Va.: U.S. Department of the Interior, U.S. Geological Survey.
Kübel, Stephen J. 1908. “The Engraving Division of the United States Geological Survey.” The Graphic Arts and Crafts Year Book 2: 75–78.
Phillips, Hugh. 1997. “Copperplate Engraving for the Production of Topographic Maps at the United States Geological Survey, 1890–1953.” Meridian 11: 5–21.