Before 1824: Invention of lithography

In 1798, Czech inventor and artist Alois Senefelder invented the process of lithography. As a result of his experiments with calcium carbonate and greasy ink, he devised a method of producing multiple copies of his artwork and writings. 

Senefelder also discovered an important benefit of lithography, whereby images printed on paper could be transferred back to another stone, preserving the original stone. This paved the way for 'ganging up' multiple images for printing.

  

1860 to 1880: Printing procedures for reproduction of maps

The following is the method used to prepare maps for publication in Queensland from the 1860s, using the lithographic process.  

After compilation of a map by a cartographic draftsman, a specialist lithographer transferred the map to a printing stone (specially imported limestone from Bavaria). The detail was traced in reverse onto the stone using 'greasy ink'. The lithographs were printed from this stone with a slow production rate of 300 copies/hour.

The work on the stone fattened after being used as a print master. This consequently made the original unsuitable for further reproduction. However, before this occurred, the stone was inked and a paper copy 'pulled'. 

Whilst the ink was still wet on the paper, it was dusted with a fine red powder, known as raddle or dragon’s blood. The powdered copy was very carefully placed on a new stone and was then run through the press, leaving a powdered impression on the stone. The edges of the sheet were glued in position around the stone. 

Small sections of a protective paper cover were gently raised to allow redrawing of the work without disruption to the remainder of the powdered image. 

During this period, production of a coloured map containing, for example five colours, would require the preparation of five such separate powdered impressions.

The stones were heavy and fragile. It was important that they were perfectly aligned with the paper to retain registration integrity. The final output quality and texture was exquisite.

  

Government printing building, Brisbane, 1869

1881 to 1900: Lithographic stone copied

Printing from the original stone was discontinued during the late 1880s. To prolong the useful life of the originals, the process was modified. A copy of the original was taken as described above and was then transferred directly to another stone from which the printing was done.

Original printing stone

1901 to 1920: Advancements in printing processes

Toward the end of the First World War, great advances were made in map reproduction, especially in the direction of printing from metal plates. 

The limestone quarries in Bavaria were mostly destroyed during World War I. This formed the catalyst for the replacement of stone plates with zinc and aluminium plates.

However the process of printing from stone remained in Queensland for many years.

1921 to 1950: Zinc plates replace stone

The revolutionary method of printing from zinc plates, rather than stone, was introduced in the early 1930s. This resulted in a saving in process time and improved accuracy in the scale of the lithographs.

Large format cameras

  

Hunter Penrose camera

 

Compilation of a map on the copyboard before reproduction

 

During the period from the 1940s to the late 1960s, the Hunter Penrose 35 inch x 45 inch Gallery Camera was used for photographic reproductions in the Survey Office. The camera produced large format negatives on hand-coated glass plates. 

The photographic emulsion was a light-sensitive coating made up of silver salts known as halides, suspended in gelatin.

 

The image shows a 'pieman' transporting glass plate negatives.

Coating the emulsion to a glass plate

 

The glass plates were progressively replaced with flexible, coated film used in the offset lithographic printing process. 

The Survey Office replaced the Hunter Penrose camera with a 50 inch x 50 inch Cartographic Klimsch camera in 1970. A second 40 inch x 40 inch Klimsch camera was commissioned in 1984 to remove the backlog created by the conversion to metric mapping. 

Both Klimsch's are still in use today, copying historic plans and images for archival preservation.

The Cartographic Klimsch camera in the Survey Office

1951 to 1985: Offset lithography

It was toward the end of the 1950s and into the early 1960s that the process of offset lithography became popular with printers. Offset lithography was an extended technology of lithography from stone. These essential processes are still used today.

As with lithography, the general principles of this process work on the foundation that water and oil repel each other.  Secondly, the ink is offset from the plate to a rubber blanket and then from the blanket to the paper.

The offset machine consists of three main cylinders. The first holds the alloy plate containing the image, whilst a rubber blanket is fastened to the second cylinder. 

The image is transferred from this blanket to the third cylinder carrying the paper. This last cylinder is known as the impression cylinder.

The printing plate's image area is rendered oil receptive and therefore water repellent, while the non-image areas are water receptive and ink repellent.

  

1986 to the Present: Digital print workflows emerge

The use of 'computer to plate' (CTP) and associated workflows emerged onto the print scene in the early 1990s, but it was fraught with inconsistencies and workflow peculiarities. 

Technology has now advanced the integrity of the CTP processes. Printers' confidence in today's technology has seen a rise in the number of units worldwide. It increased forty fold during the period from 1995 to the end of 2002.

Over the previous fifty years before the emergence of CTP, a film-based workflow was used. This was a straight forward process starting from map compilation through to the print stage. Each step in the workflow was a distinct, separate operation. 

Digital technology changed the way in which workflows now progress. Each progression melds into the next as a seamless operation, performed transparently using specialised workflow software. 

The complete procedure is now a digital process until the original digital file is transformed into printer's plates.

Benefits of CTP over the more conventional film process include improved print quality, reduced time and labour costs, flexibility and more efficient production workflow strategies.

The quality of final output using CTP is inherently better because there is only a single generation screen dot in the plate. Therefore the result is a more sharply defined printed halftone dot.

However, film production is still widely used fourteen years after the introduction of CTP. This is primarily due to initial changeover costs, and will most likely continue to be used for some time.  Film still rivals the CTP alternative in both proofing and printing.^{Adapted from Australian Printer April 2003, May 2004}

State of the art offset printing press  ^{Platypus Graphics 2004, Brisbane}