Map Printing Methods

By Joseph H. Fitzgerald

The earliest maps were cut on stone or drawn on clay tablets. Later maps were drawn on stone using various pigments found in nature. Few examples of these maps exist and none show Florida.

Manuscript

The ancient maps were drawn on papyrus or vellum (parchment), animal skin specially cleaned and bleached. They were colored with various pigments. Often only one copy existed or scribes made a few copies by the same drawing methods. The method of drawing so-called manuscript maps was used by the ancient Greeks and later by the makers of the so-called Portalans or sailing charts during the early Renaissance. Copies of these early manuscript maps have been made by various methods since the invention of printing.

Printing

Printing was said to be invented to Johannas Gutenberg in Mainz, Germany in about 1455, but what he actually invented was movable metal type. The printing of maps did not rely on movable type and therefore was done prior to this time.

Woodblock printing or relief printing was the first method used. It involved cutting out a design in relief on a block of wood, that is the design was left on the surface after the spaces between were cut away. The ink was applied to the surface portion and not allowed to run into the cut portion. The paper (or vellum) was then pressed onto the woodblock and picked up the ink from the surface of the wood. The printed portion of the paper, depending on the pressure, was compressed because the paper had been moistened slightly before pressing in order to pick up the ink more easily. Maps or prints made in this way are called "wood cuts" and this method was used until the early1500s.

Wood Engraving

Using the end grain on a block of wood a design could be cut into the wood in fine lines. Then the paper was printed in the same way as in copper engraving. Maps made in this way are called "wood engravings" and the method was used concurrent with wood cuts.

Engraving

The earliest attempts at engraving were made during the mid 1400s but the method was not used extensively until the mid 1500s.

In engraving, a design in reverse is cut with a burin into metal, usually copper or steel. The ink is rubbed into the grooves cut in the metal, and the excess ink is wiped off the surface. This leaves ink only in the engraved or cut out lines. The paper is then moistened and pressed onto the metal plate with great force, picking up the ink in the grooves. This method of printing is called "intaglio". The great pressure required leaves two kinds of imprints on the paper. One is the "bite" or lines made on the paper where it was pressed into the grooves in the metal. This corresponds to the printed part and is usually microscopic. The other distortion of the paper is the line or dent around the edge called the "platemark".

These features are useful in identifying original old maps and help to distinguish them from photocopies or facsimiles. The platemark has nothing to do with the watermark. Because of the softness of the copper used for the engraving, the plates could be used only for several hundred or a thousand copies before some lines become faint. The method was tedious and time consuming but was used extensively until the mid to late 1800s.

Etching

A design can be etched or eroded on a metal plate by acid (usually nitric acid). Zinc is the best metal for the purpose. After coating the surface of the plate with a mixture of asphalt, beeswax and other tars and waxes to give a hard smooth film, the design is cut through the coating with sharp instruments (scribes), exposing the metal below. The areas between the incised lines are left coated. The plate is then immersed in an acid bath that bites or etches the exposed metal. The coating is then removed and the plate is ready to be inked for printing as in any other intaglio or engraving process. Etching is still used in the photo engraving process.

Steel Engraving

After the invention of mechanical presses and the popularization of printed materials in the late 1700s and early 1800s, the need for a metal capable of producing thousands of pulls from a single plate led to the use of steel instead of the softer copper for engraving plates. Steel engraving allowed for very precise lines and great detail but proved to be so tedious and time consuming that it ceased to be used.

Lithography

In 1796, Alois Senefelder of Bavaria discovered that Solenhofen limestone from near Munich had an affinity for both water and grease. When drawn on the limestone's flat smooth surface, a grease-based ink will adhere to the stone surface. The stone is washed with a solution of water and nitric acid to wet the bare portion. The stone is then inked with a roller, the ink adhering only to the greased lines. Next paper is pressed onto the stone surface lifting enough of the ink off the stone to give an outline on the paper. This is a planographic method based on chemicals rather than a relief (wood cut) or intaglio (engraved) method. Because of the use of a stone slab the method is known as lithography (lith=stone). It is cheaper than copper engraving and was used to make multiple copies of earlier maps until the advent of photo engraving early in the 20th century.

Chromo Lithography

Until 1836, all coloring on maps was done by hand. The development of color lithography was the achievement of Godefroy Engelmann (1788-1839), a Frenchman. The method involves reprinting the map for each color or combination of colors. Great care must be taken to align the paper carefully so that the colors do not overlap the boundaries. Chromo lithography was used in the production of many facsimile atlases for the remainder of the 19th century. The substitution of zinc plates for stone was useful in power presses.

Photo Lithography

In 1814, Joseph Niepce found that bitumen became insoluable when exposed to light. In collaboration with L.J.M. Daguerre, he invented practical photography in 1839 in Paris. The process exposed metal plates coated with silver iodide to light by means of a camera obscura, the plates were then developed by mercury vapor. Working independently, William Henry Fox Talbot developed a similar process in England.

Over the next 50 or 60 years, further developments in chemistry and technology made printing from photography feasible. The basic process involved coating a stone or metal with a photosensitive gel that hardened when exposed to light and that could then be washed off the unexposed surface. The metal surface was then etched with acid and the printing process carried out as with any kind of relief or intaglio printing. Several methods were developed. The invention of artificial light (1880) and a power source to produce it were the indispensable preconditions for these processes.

Offset Printing

This process consists of transferring the image on a rotating zinc cylinder to a rubber mat on another cylinder and then allowing the image to be "set off" onto the paper. The combination of these two developments together with the high-speed press allowed for cheap, accurate, mass production of maps.

Computers

With the advent of new sensing techniques and photography by satellites, information is transferred directly to a computer where it is stored, sorted and displayed in a variety of ways: on a cathode ray screen, on microfilm, or printed on paper. The maps produced by satellite imagery and computer technology since 1950 are called orthophotomaps.

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