METROPOPOSTCARD GUIDE TO PRINTING TECHNIQUES 1
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Traditional Printing Techniques


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INTAGLIO PRINTING METHODS


Intaglio is a low relief process in which a sheet of metal is incised with the aid of hand tools or with acid, and the depressions filled with a stiff ink into which paper is pressed by means of a high pressure roller. This method produces a high density of printed ink that lays in relief on top the paperŐs surface, creating a dark rich picture. Images in intaglio are created either with narrow lines or small marks for if the incised areas are too broad the plate will be unable to hold all the ink. The edges of the metal substrate (plate) are beveled so not to cut the paper while under the extreme pressure of the press. This leaves behind an embossed ridge around all four edges of the print known as a plate mark. Intaglio began as a line technique first used by metalsmiths for creating decorative works. As printers appropriated these methods, line etching and engraving became the most common traditional uses of this medium. When intaglio began to be used to reproduce works of art a wider range of incising methods were developed to better create tonal effects. Even though intaglio printing has been around since the 16th century, its commercial use has been restricted to low volume printing because of its high cost and the poor durability of plates created by certain methods.

It must be noted that while printing plates can be created through a wide variety of intaglio methods, they are not exclusive of each other. Many artists employ a number of techniques on a single plate. To save time, many commercial printers placed their initial drawing on a plate in either drypoint or etching to act as a guide for the time consuming process of engraving that followed. Despite the different techniques used, many of these works are characteristically just referred to as engravings. Even when etching was used exclusively in a reproductive capacity by commercial printers, the finished piece was usually called an engraving. While this form of generic labeling may have just arisen out of convenience, references to engravings may have been purposeful in that they were then considered a higher form of the art that might fetch more money. This inappropriate use of terms has also unfortunately led to many artists being mistakingly referred to as engravers when they have never made anything more than etchings. Many painters dabbled in drypoint or etching because it was similar to drawing. Engraving was a very different skill often carried out by craftsmen.



Rolling Press
The rolling press was first used for the manufacturing of sheet metal and the calendaring of fabric before it was adopted for printing in the 16th century. It proved perfect for intaglio printing, which required a great deal of pressure to force paper into the fine lines of an incised plate. Both the plate and paper would be placed together on a flat press bed and then covered with felt blankets for cushioning before being squeezed between two heavy rollers. Wooden presses were eventually replaced with those of all metal construction so even heavier pressure could be employed for a better transfer between plate and paper. This basic method continues to be used by artists working in intaglio today, but it proved to be much too slow for most commercial printing. This design would eventually evolve into the cylinder press, patented by Friedrich Konig in 1811, and then into a practical rotary press by the mid-19th century.

Illustration

Rolling Press: This illustration of an early hand press with a bed sandwiched between two heavy rollers was designed to print intaglio plates. While commercial printing would move to steam powered then electric rotary presses, this 400 year old design continues to be employed on modern presses used to pull hand printed images.




ENGRAVING

The earliest form of intaglio is engraving, long used to decorate metal before ever applied to a printing plate. Engravings are made by incising a metal sheet with a specially designed burin. This tool cuts and pushes metal out of the substrate leaving behind smooth edged lines with usually at least one tapered end. The primary difficulty in working with a hard metal substrate has generally meant that engraved lines must be cut decisively and with care. These demands dictate a certain uniformity between the look of all engravings, which often has a stronger influence on the final product than anything the individual artist can imbue. While any metal can be engraved, copper was the substrate of choice because it is softer than most thus requiring less effort to incise. Since metals are made up of crystals, they can directionally align when being rolled into sheets. Another advantage to using copper is that it lacks this directional grain that can interfere with the cutting smooth curved lines. This process is sometimes referred to as line engraving. While a line can be made darker by widening it through a deeper cut, tone was usually created through crosshatching.

Engraving plates are printed in a traditional intaglio manner by covering the entire substrate with a stiff ink and then wiping the top surface clean. Engravings tend to be very durable due to the crisp sharp edges of the lines and their depth, making them suitable for large press runs. The process of engraving however is very time consuming and it is also a highly skilled craft that generally made it too expensive to use in the production of ordinary postcards though they can be found.

Metal Engraving Tools

Metal Engraving Tools: The top three gravers pictured above are angled differently to more easily conform to the engraver’s hand as it moves across the plate. At the bottom is a stipple graver that is angled to work better with downward pressure. The width and depth of an engraved line is totally dependent on the relationship between the diamond shape tip of the burin that cuts it and the amount of pressure that is applied by hand as seen in the illustration below. When engraved lines are placed close together on metal they can be made to print a solid black though the lines are still evident in the texture of the ink. This is due to the strength of the substrate combined with the angle of cut that is placed by a deliberate hand.

Illustration


Engraving Detail

Line Engraving: Both of these details illustrate the evenly tapered carefully incised lines so characteristic of the French style of engraving. All burs turned up by the graver that might collect ink have been removed to insure a clean printing image. While this gives it a more artificial look, the consistency provided made it a favorite among commercial printers. Even though various styles of engraving developed in different European nations, all engraved lines are best controlled when laid down parallel to one another.

Engraving Detail


Postcard

Engraving: This postcard from 1908 has more engraving on it than typical currency. In the detail below we can see that lines can be created in a number of different ways and some even print as solid blacks.

Postcard Detail

Stipple Engraving
A variation of line engraving is stipple engraving, where small holes are gouged out of the metal plate. It was sometimes used in conjunction with line engraving, and a technique known as opus mallei was also developed in which and entire image was created with small dots. These dots were originally hammered into the plate with an awe but a specialized metal punches with a random array of dots on its head (mattoir) were later developed. These tools were largely replaced by a more angular graver designed for use with downward pressure rather than across and up as with a typical line cutting tool. There is a tendency in stipple engraving for the flecked up metal to remain attached to the plate and when ink gathers around these burs as in drypoint, it creates an even softer looking print. Stipple engraving became popular in the mid-18th century when its greater ability to create the illusion of tone though an accumulating density of marks made it ideal for reproducing crayon drawings on rough paper. New tools were also developed to create tone such as textured cylinders at the end of wooden handles (roulettes) that were rolled over a plate’s surface to roughen it up. While very delicate tones could be created with all these tools the popularity of stippling died out in the early 1800’s. Even so stippling has remained in use and can be found on postcards in very small numbers.

Postcard

Stipple Engraving: Although the postcard above mainly consists of line engraving, it also employs a fair amount of stipple engraving, especially to render the more subtle highlights in the face and create smooth gradations in tone as seen in the detail below.

Postcard Detail


Postcard Detail

Stipple Engraving: This detail shows how stippling can also be used to create flat even tones, in this case to fill in the broad spaces between heavier line engraving. To some extent this technique was employed on postcards for its decorative qualities as much as its ability to produce true tonal effects.


Copperplate
Although engraving was considered the highest form of 19th century illustration, the technique was not compatible with letterpress that dominated the printing trades. Even if an engraved plate was raised to the same height as type, its manner of inking was so different to render any consideration pointless. If engravings were desired in book form they needed to be printed separately then sewn or tipped in during binding. Titles, captions, and small bodies of text such as lines from poems or songs were sometimes engraved into the border of these pictorial plates. This result of this common practice of combining engraved lettering with an image is called copperplate. This name should not be confused with engravings made from the printing of copper plates.

Steel Engraving
Iron had been used for both etching and engraving since its inception. Its hardness allowed many impressions to be pulled but the same quality made it difficult to place an image into it, and its susceptibility to rust kept it out of general use in favor of copper. In 1797 Jacob Perkins patented a method of softening steel for engraving upon it with hardened steel tools, and then casehardening the plate afterwards for printing. The durability of these plates allowed steel engraving to become a competitive printing medium until the method of electroplating copper with steel was invented. The deep relief of this surface allows steel engraved plates to be wiped completely clean without fear of removing too much ink from the lines. This not only speeds up printing but creates identical sharp crisp images that are more difficult to forge as no plate tone residue is left behind to create unique impressions. Though used to reproduce numerous images, this process was not well liked among illustrators because of the clean sterile look that it produced.

Steel Engraving

Steel Engraving: Most steel engravings have a uniform look do to the slow meticulous way that this hard metal was cut into. In this detail however we can also see some of the great variety of ways that lines so characteristic of this process were cut.

Steel Engraving: Detail

In 1806 Perkins elaborated on this technology to create multiple yet perfectly identical engraved printing plates. A soft steel roller was pressed against a hardened steel engraving under great pressure until it was forced into all the lines. After the roller was hardened it would then pass over a new soft steel or copper plate and press its ridges into it. Many plates all with identical lines could be made this way to speed up production. Even after photo technology made it easier to create multiple plates, this method continues to be used to print money, stamps and certificates where millions of copies are needed.

Steel Facing
While printers liked steel for its durability, it still proved a difficult substrate to work on even when softened, and artists were reluctant to use it. A way around this problem was discovered in 1857 when engraved copper plates began to be electroplated with iron. Engravers could continue to work on the metal of their choice while the iron coating place over it afterwards would greatly increase the plates life on the press. The layer of steel applied by electroplating was so thin that it could be used with any intaglio process without fear of disturbing the image. When the iron facing began to show wear it could be electroplated again leaving the copper beneath it in perpetual mint condition. Many other delicate processes such as aquatint and mezzotint could now be commercially printed, though still in limited quantities.

Electric Engraving
A tremendous amount of commercial prints and book illustrations were created through steel engraving but it was not used in the production of postcards until the 20th century, and even then its use was very limited. Most of the images created though this method often differed radically from their 19th century cousins as they tended to be drawn with special electric powered vibrating needles. These needles required far less skill to use than the traditional engraving burin and they made it easier to incise the hard steel substrate. While the clean wiping of the plates surface still gave them a similar appearance to that of a traditional steel engraving, the lines created with this tool tend to have a uniform depth with a very shaky uneven edge. Electrically engraved lines also end abruptly without the familiar tapering created by diamond shaped gravers. Electric engraving tools would find much more use after they evolved into electric needles used for tattooing.

Postcard

Electric Engraving: The vibrations created by electrical engraving tools not only help it cut through metal but it gives the images they make a jittery look as seen on the postcard above. While the magnified detail below from a similar card clearly reveals the uniform quality and irregular edges of individual lines created with this tool, such cards are often decreeable from hand engraving by their general look.

Postcard Detail


LINE ETCHING

Etching is an intaglio printing process by which a sheet of metal is incised through chemical means. First the substrate (plate) is coated with an acid resistant varnish (ground) and once dry it can be drawn upon with a sharp metal scribe that does not disturb the metal underneath but only removes the resist from its surface. When the plate is placed into a bath of acid, the metal devolves where the resist was removed creating an incised line. The darkness of a line can be varied by controlling the time a plate spends in the acid; the longer the chemical reaction goes on the deeper the ink holding line. By sealing off some lines (stopping out) while continuing to bite others, further tonal variations can be made. The type of metal substrate and acid used can also have a noticeable affect. Lines drawn on copper bite downwards, but if drawn on a zinc plate the lines will also widen. Lines created through an acid bite have rough edges do to the uneven chemical reaction that takes place around torn edges of the ground. Though individual etched lines are not discernible without magnification from the smooth edged lines made through engraving, the overall effect is very different and apparent to the naked eye. Unlike engraving, etched lines have a natural ease about them that can more easily to express the individuality of the artist because they are initially drawn rather than cut.

Etching Tools

Etching Tools: The picture above shows three different types of etching needles (stylus). All needles basically perform in the same way and differences are designed for personal preference in weight, grip, and cost. In the illustration below we can see how the lines drawn by these tools are eaten out from a metal plate. The longer a plate is left in acid the deeper and sometimes wider a line will become. Printing ink is held inside the etched lines and wiped clean from the plate’s surface. If a line is etched too wide and shallow, a crevasse is formed and ink will tend to only cling to its sides. If lines are drawn too close to one another they can under-bite in the acid and run into each other. While this can sometimes create an intense black patch, it will more likely open crevasse that will not hold enough ink to print a solid tone.

Illustration


Postcard

Etching: Due to the aggressive wiping of etched plates, ink tends to be removed out of any wide areas of relief on a plate. This is why tone is most often created through a technique know as cross hatching. Sets of parallel lines were drawn against each other at different angles, each set adding a darker level of optical tone. If lines are drawn to close together they may combine in the acid bath to form one large unintended hole (crevasse). The etched pattern below is unusual because lines were usually drawn in at a sharper angle to one another so a screen-like look could be avoided.

Postcard Detail

After the ground has been washed off, an incised etching plate can be printed in a traditional intaglio manner by inking the entire plate and then wiping its surface clean. Etched lines tend not to be as deep as those found in engraving so more care is taken to wipe a plate’s surface clean after inking. Too much ink can easily be removed, which will produce a mottled image. Some ink residue (plate tone) is usually left behind, which gives each impression a slightly different appearance. Under wiping can leave unintentional dark blotches behind, but in the late 19th century it became common for printers to purposely pull a little ink out of etched lines after the initial wiping to create more plate tone for artistic purposes (retroussage). Most plates used to print postcards were wiped as clean as possible but this seems to have more to do with style than technique. The lack of line depth also makes etched plates wear out quickly, so this method was rarely used for commercial work. Most etched postcards were printed in the early 20th century by artist cooperatives or small publishers in limited numbers. Some cards even have blank backs, which may indicate they were printed by the artists who drew them. When larger quantities of etched postcards were desired, facsimiles were often produced in a more durable medium.



TONAL INTAGLIO TECHNIQUES

While delicate tones can be created though the careful and laborious manipulation of crosshatched lines, etching largely remains a linear technique. The ability to produce large tonal areas with soft transitions more efficiently had both aesthetic and practical value, and so a number of methods were developed to create it. Attempts to simulate the appearance of washes were largely fueled by commercial efforts to reproduce paintings and watercolors. Unfortunately the various textures that produced light tonal values from metal plates proved to be much more fragile than etched lines, and they wore down quickly under the heavy pressure of the rolling press. These techniques largely survived only because they proved adequate for artists to work with, but they were not suitable for larger scale commercial printing. This changed to some degree when they were adapted to steel facing, but even then the shallow quality of these plates remained problematic. Only two of many tonal methods, aquatint and mezzotint are discussed here for they have some relevance to postcard production.

Aquatint
The intaglio process called aquatint was in use since the 17th century to get around the limitations of having to manipulate line to create a tonal range. In this process a metal substrate is dusted with a fine powder of rosin or asphaltum that is then adhered to its surface by applying heat from underneath. The tiny melted particles act as a chemical resist so that when the plate is exposed to an acid bath, an irregular pattern capable of printing tones will be etched into it. These patterns can be somewhat controlled by varying the amount of dust applied, the size of the crystals in the powder, the amount of heat the plate is exposed to, and of course by the length of time the plate is etched in acid. By painting on an additional acid resist (stop out) to selected areas of the image during the etching process, some parts can be covered to print white or a full range of tonal values in subsequent acid baths. Plates holding etched aquatint patterns can also be burnished to shallow out their ink cells, which in turn will bring it up to white or just lighten its tone. The surface of aquatints are very shallow rendering them very susceptible to wear, so they do not hold up well to the large press runs required by commercial printing. Its use for the most part was replaced by lithography in the early 1800’s and rarely employed afterwards outside of the fine arts except in very limited printings. While not used to produce postcards in its pure form, the aquatint process was eventually combined with photogravure to give it a finer more even texture.

Spirit aquatint was another aquatint technique that largely fell out of use at the beginning of the 20th century. Rosin or asphaltum were dissolved in alcohol and then painted onto a plate. Once the alcohol evaporated, an acid resist full of small irregular cracks would be left behind that could be processed like a traditional dust aquatint.

Aquatint

Aquatint: This intaglio image was largely created through the use of aquatint. It has a strong painterly quality due to the stop out varnish that was applied to the plate with a brush between the biting of different tonal values. In the detail below we are presented with its rough aquatint surface. While all aquatint patterns are irregular often due to variations in grain size, we are confronted here with wildly shaped white patterns created where many rosin crystals fused due to overheating. While this is theoretically a flaw, such mistakes can also be used to further artistic effect.

Aquatint:

An aquatint with a very coarse grain can be achieved by employing a spirit-ground instead of rosin dust. In this method the rosin or asphaltum powder is dissolved in alcohol and this solution is then painted over a metal plate. As the alcohol evaporates the small amounts of resin left behind cannot cover the entire surface and this thin film will reticulate into a random pattern. It is then etched in the same manner as a powdered aquatint. The amounts of white produced within the pattern could be somewhat controlled by varying the dilution ratios of components, but this is difficult to control. Only a few printers were using this process by the late 19th century, though it seems possible that it may have seen more utility in conjunction with some photomechanical techniques arising at this time.

Mezzotint (Manièrre Norie)
In the technique of drypoint, a metal plate is drawn upon with a stylus using just enough downward pressure so that it pushes up a bur along one edge of the line. Both the incised line and the edge under the bur will hold ink, and when wiped for printing the ink from under the bur spills out creating a soft fuzzy looking line. Ludwig von Siegen coupled this concept with stipple engraving to create a process in which an entire metal substrate is covered with small jagged dot-like impressions that will create rich blacks and subtle tonalities when printed. Soon after in 1657 Prince Rupert of the Palatinate sped up the process by substituting the hole producing burin with a heavy curved blade holding a serrated edge (rocker) that is rocked back and forth across the plate’s surface to create lines of small incised dots. When the entire surface of the plate is covered with near parallel lines a new set of lines are rocked onto the surface at a different angle. This step is repeated a number of times until no discernible line pattern can be seen.

Mezzotint Rocker

Mezzotint Rocker: This picture of a mezzotint rocker shows the blade side of the tool. The other side has been cut with narrow rows of evenly spaced grooves so that they taper to a sharp point at the blade’s edge. When rocked across a metal plate a line of fine dots will be left behind. The rocker does not just create holes in the substrate it rips up its surface creating accompanying minute metal burs that also hold ink as in drypoint. The picture below illustrates the surface of a mezzotint plate with a patch of burnishing put in to lighten tone and create white.

Illustration

If a freshly rocked mezzotint plate was printed, it would yield a solid black. To create an image its burs and holes must be burnished down to form grey tones or completely removed to bring back whites. Since no lines ever need to be drawn, this subtractive method often lacks personal style, which made it ideal for capturing the style of others when reproducing paintings. The burs created by both drypoint and mezzotint are very delicate and they wear down quickly with every pass through a press. This makes the process useless for commercial printing where large press runs are needed. The textural surface of mezzotints however is alluded to in other look a like printing methodologies and in trade names that wish to impart that their image captures the same high quality tonalities.

Mezzotint Detail

Mezzotint: This detail displays the typical smooth transition of tonal values printed from the burnished surface of a mezzotint plate. There is some sense of its linear origins but the surface is just too chewed up to decipher any patterns, which of course is the objective.



COLOR INTAGLIO

High pressure is used in intaglio printing to force paper into the incised lines of the plate where it will pick up ink. To aid this process and prevent buckling the printing paper is softened beforehand by soaking it in water to remove some of its sizing. Since intaglio inks are stiff and are applied thickly the absorbency of the paper is of little concern and sizing can easily be sacrificed in return for pliability. Under the pressure of the heavy roller the wet paper will stretch out and immediately begin to shrink as it begins to dry, never regaining its exact original shape. This generally goes unnoticed in black & white printing but in color work were the precise alignment of multiple plates are required this shrinkage proved to be very problematic. While color intaglio prints were made with multiple plates, the process was too difficult for most commercial printers to consider, especially after alternatives like lithography became readily available.

À la Poupée
Even though most color intaglio prints were produced through the use of multiple plates, any type of plate could receive multiple colors by a method known in French as à la poupée, (with a doll). In this process any number of different color inks are applied onto a single substrate usually with the aid of small hand held cotton daubs (dollies), though different tools can also be used. While adding color to just one plate eliminates registration problems, sharp and precise color delineation cannot be achieved and the coloration of individual prints created through this method will vary in appearance. Not only is the application of colored inks by hand indecisive, the hand wiping of a plate’s surface pulls colored ink out from the lines causing them to mix unpredictably wherever different hues meet. Between these variables and the time consuming nature of this method, it was not viable for commercial printing. Though mostly employed by artists since the late 1600’s, this type of inking can be found on etched postcards that were already being printed in very limited numbers.

The physical act of aggressively wiping the surface of an intaglio plate clean could also cause problems with color printing that discouraged its use. Depending on the chemical composition of the hue and the type of metal substrate used, wiping could pick up metallic particles from abrasion and add them to the pigment altering its color. While any change of color largely goes unnoticed when working with black ink, colors such as yellow printed from a zinc plate can easily gain a greenish cast.

Postcard

À la Poupée Etching: The reds, greens, and blues on this etching were all placed in by hand before the rest of the plate was inked with a dark brown. As the excess ink is wiped from the plate’s surface before printing, the colors are pulled from their lines and begin to merge.





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