METROPOPOSTCARD GUIDE TO PRINTING TECHNIQUES 1
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Traditional Printing Techniques


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FUNDAMENTALS OF PRINTING


Papermaking originated in China but it is such an ancient art that the exact years and circumstances of its origin are unknown. Agents of the Byzantine Empire are known to have imported paper from the Arabs who had been making it since the 8th century. Its manufacture began in Europe after arriving through Muslim Spain where it was used to fuel their great libraries. Prior to the introduction of paper, text and images for books were rendered by hand on animal parchment. This was a costly endeavor as the making of a large Bible could require the slaughter of as many as 300 sheep. Even though paper simplified the production of books, it was still a slow process performed by hand. Over all this time, the process of making paper remained basically the same. It begins with some form of pulp consisting of organic fibers suspended in water that are poured over a flat screen and left to dry. While the invention of the printing press in 1440 was revolutionary, it was only the innovations in paper production that began in the late-17th century that allowed printing to become a large scale commercial enterprise.



PAPER

Papermaking originated in China but it is such an ancient art that the exact years and circumstances of its origin are unknown. Agents of the Byzantine Empire are known to have imported paper from the Arabs who had been making it since the 8th century. Its manufacture began in Europe after arriving through Muslim Spain where it was used to fuel their great libraries. Prior to the introduction of paper, text and images for books were rendered by hand on animal parchment. This was a costly endeavor as the making of a large Bible could require the slaughter of as many as 300 sheep. Even though paper simplified the production of books, it was still a slow process performed by hand. Over all this time, the process of making paper remained basically the same. It begins with some form of pulp consisting of organic fibers suspended in water that are poured over a flat screen and left to dry. While the invention of the printing press in 1440 was revolutionary, it was only the innovations in paper production that began in the late-17th century that allowed printing to become a large scale commercial enterprise.

While a seemingly simple device, the Holander beater that could quickly break down rags into large quantities of paper pulp replaced the slow grueling task of shredding, beating and grinding by hand. When combined with James Whatman’s invention of a fine screen that produced the first smooth finished Wove paper, quantities could finally be produced to meet the fast growing demand. By the first half of the 19th century, nearly all traditional hand made papers were replaced by those made by machine. Within forty years the entire industry had been mechanized. In 1798 Nicholas-Louis Robert became the first to figure out how to make paper in rolls (webs). After Thomas Bonser Cromton perfected this machine for commercial use in 1820, rolled webs became instrumental in speeding up the printing process and led to the development of the Flatbed Cylinder Press. Most postcards however would be printed on slower sheet fed presses.

Paper in the 19th century tended to be made from cotton, hemp, and flax, which were usually obtained from the beating of cloth rags, hence the term rag paper. The invention of the horizontal loom and spinning wheel had made the production of linen clothing cheap and plentiful, which in turn insured a continuous supply of rags for the manufacture of paper. Rag pickers filled city streets to help supply hungry mills. Wood was sometimes milled into pulp as a cheep alternative to the more costly rag but it produced a weak paper. Eventually a chemical process was developed that was able to break down wood fibers into purer cellulose that created stronger bonds. Though this chemical process replaced the slow laborious task of grinding wood, it was not often used until the 1870’s when methods of removing the vast impurities within it were developed. This new way to process wood not only brought down cost, it greatly increased the supply of paper so urgently needed by the fast growing printing trades.

Generally most postcards were printed on paper made from cheaper chemical pulp (wood cellulose), which gave them a hardness and limited durability. It is the chemicals leftover from breaking down the wood that causes cards to yellow over time, usually in direct relation to the quality of the paper used. As the percentage of wood content in paper increases so does the destructive power of acid residue. Several layers of paper would be pressed together to create card stock, then coated with China clay to help prevent ink absorption. The reflective property of the light clay surface also helps to brighten the image printed over it. It wasn’t until the latter 1800’s that a practical wood pulp, card stock, and coated papers all became available to the printing trades.

Postcard

Paper Webs: This postcard from 1906 depicts printing paper being rolled into webs at the mill in Maine where it was manufactured.


Modifications
The so called Laid papers we use today are a far distant cousin from their earlier relations. The watermarked lines they now contain are usually placed there for decorative purposes and are unrepresentative of the highly uneven surface that results from laying pulp over a linear wire mesh during production. It was from the wire mesh techniques used to make silver and gold cloth that a tighter and more even screen for papermaking arose. The smoother Wove paper these new screens produced proved to be the perfect substrate to print on but it also left printers with two basic problems. One was that the natural absorbency of paper soaked up ink, which created a good bond but diluted the intensity of the image. As pigment migrates into paper it is masked by fibers that prevent light from reflecting off of it and back to the eye creating dull colors and soft edges. Even on Wove paper the natural roughness of cellulose fibers were another problem as they could diffuse finely printed details. Both of these problems were partially solved by compressing paper under heavy polished rollers once they dried. This process is known as calendering producing cold press, paper and when the roller is heated to create an even smoother surface, it is referred to as hot press. Various textures can also be embossed into the paper at this stage by creating a textured stereotype for one of the rollers.

The remaining absorbency issue was solved by adding a nonabsorbent coating such as starch, casein or glue to the paper’s surface. While the adding of a water soluble sizing became common practice, more durable coatings such as China clay (kaolinite), once used in the manufacture of porcelain became widely adapted for printing papers. It created a bright glossy surface that produced richer colors and darker blacks by subduing light scattering and by masking the properties of natural paper fiber. In 1885 a similar baryta coating (barium sulfate mixed with gelatin) began being used to size photo papers before the photosensitive emulsion is applied. Coated papers were well suited for lithography but not intaglio printing where the paper is routinely soaked before printing to remove most of its sizing. This is a necessary step to allow paper to better stretch under the high pressure of the press and be pushed into the incised lines of the plate. Gravure is the only exception since it requires far less pressure to create a printed image from its shallow surface.

Texture
While the purpose of cold and hot press processed paper was to generally reduce the rough surface that formed while it dried on a screen, the heavy rollers that were employed were sometimes given the extra task of embossing a specific texture directly into the paper. The patterns on these special rollers could be incised right into them by photo-mechanically transferring an image and then rotating them in an acid bath. Most of the patterns produced are so delicate their details cannot be discerned by the naked eye, which creates the impression of a natural rough surface. More noticeable geometric patterns were also embossed into paper, the most common of these being small rectangles placed in waffle like grids that produced the illusion of linen texture. The texturing of paper for the most part was originally done just to add to the appeal of the final product by implying associations with artwork such as paintings on linen canvas. In the 1930’s the practice of embossing would gain more practical applications as an aid in speeding up the drying time of dye based inks.

Postcard

Embossed Paper: The dirty surface of this detail from a postcard made in 1905 helps bring out the wormy pattern embossed into this paper. The edges of the embossment are actually more sharply defined than what can be seen here, and under magnification it is impossible to confuse its regularity with the haphazard natural fibers of paper that has not been pressed.



PRINTING INK

The inks used in the printing trades have been carefully adapted to each printing medium resulting in a wide variety of product; those used in lithography are the consistency of tar, and those used in screen printing are similar to house paint. In the 19th century it was the new scientific field of organic chemistry that brought real changes to ink. Many new synthetic colors were developed that were a boon to the printing trades and no doubt fueled both the interest and ability to create chromolithographs. Unfortunately many of these new colors proved to be fugitive and either faded or changed color over time. As fierce competition grew between England and Germany to invent and patent new synthetics, more careful research was done to insure color stability, but a reliable pallet for printing would not be found until well into the 20th century. These problems may have influenced the general scaling down of colors used to make postcards as much as economic incentives, but the lack of pure hues would also hamper those attempting to apply prevailing color theory to simplify printing methods.

In 1925 six major German companies merged into one giant cartel, IG Farben (Interessen-Gemeinschaft Farbenindustrie AG) to become the world’s largest manufacturer of chemicals including inks and dyes. Prior to World War One these companies already had a near German monopoly, which gave them control over 88 percent of all colorants. Few nations took notice and just imported their inks from Germany until the outbreak of hostilities brought about embargoes and blockades. As ink supplies dwindled, a worldwide crisis within the printing trades arose and the palette used for postcards came to have more to do with available supplies than with actual need. In the postwar years, the manufacturing of inks became more global though Germany still held an edge until World War Two. The many trade secrets taken as part of war reparations helped the United States become the world’s largest producer of ink.

While colorants played a major role in postcard production, not all of them were in the form of ink. Countless postcards would be hand colored in the tradition of popular prints. This was usually done through watercolor, which soaks into the paper leaving ill defined edges behind. If a color is uneven and exhibits no discernible grain it is most likely a water based paint applied by hand with a brush. Some postcards were more than hand colored, they were entirely hand painted. The clue to discovering these cards is in the way the colorant lies on the paper. If created with paints other than watercolor they will sit on top of the papers surface and sometimes show indications of brush marks. Many such cards were produced by artists throughout the 19th century, not necessarily to be used as postcards but as tokens and souvenirs.

Postcard

Handmade Card: This postcard was created entirely with an opaque paint, probably gouache. In the detail below we can see the unevenness of tone and surface texture as well as rough outlines in the paint as a result of being applied by a brush.

Postcard Detail



PRINTING PRESSES

The basic design of the printing press had remained the same for centuries, but when change finally did come, it continued to evolve at an ever increasing rate. The impetus to generate new technology was not driven by new discoveries but by the growing demand for printed material in a world where literacy rates were suddenly climbing. Few books and newspapers had been needed when most people could not read, but as schools became more commonplace and literacy rose, the printing industry barely found it possible to keep up with demand. Without this general trend the printing trades would have remained a minuscule industry and there would be no such thing as postcards, at least not in the way we have come to know them.

Screw and hand Presses
The first presses designed for typographical printing were similar to those used for pressing grapes for wine. A pressing board suspended on vertical runners was attached to the bottom of a large screw. As the stationary nut that surrounded the screw was turned, it forced it and the pressing board downwards until it squeezed what lay between it and the press bed. In this manner inked type was pressed into a sheet of paper. By the 19th century screw presses had become obsolete for commercial printing because they were just too slow to compete with the newer bed and platen models. A much smaller version known as a hand press would have a much longer life and play a role in postcard production. These easy to use hand powered devices were often used by small businesses not related to the printing industry, and even amateurs at home could print up small paper products in low quantities because of the ease of setup. Their existence in small shops all over the country would eventually create the climate for the stock postcard. Establishments who did not have enough customers to order a full press run of an original image could buy small quantities of generic cards and use their small hand press to customize them. This method allowed souvenirs to be made of any location and specific events or a particular product could easily be advertised. This procedure became a common practice with trade cards before it was used in conjunction with postcards.

Postcard

Screw Hand Press: This modern postcard reproduces an old woodcut dating from 1522 displaying a Badius hand operated screw press in action.


Bed and Platen Press
Two types of presses have dominated the printing trades since the early 19th century. One was the Bed and Platen press where paper is laid over an inked form on a flat bed and then pressure is applied by means of a heavy metal plate that squeezes them all together. Though based on the principals of the screw press these more efficient machines had no screw, their mechanisms opened and closed through the use of weights, counterweights, and springs. They could be powered by steam and still be operated by pressmen utilizing traditional skills. By mid-century much commercial work had switched over the speedier cylinder press, which had proved its excellence in printing newspapers and large book editions. While the cylinder press became the chief competitor to the platen, it required special training to use and was not suitable for printing smaller items or those needed in more limited quantities. To meet these special needs Daniel Tredell of Boston built the first small scale version of a platen press in 1818 that became known as the Jobbing Platen. It was basically an American invention eventually manufactured in many varieties to satisfy specific needs. Many of these old models were still in use well into the 20th century. Both of these press types have played an important roll in the printing of postcards since their inception.

Illustration

Bed and Platen Press: This English made Minerva from about 1880 is a typical design for a small jobbing platen press.





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