Photozincography, sometimes referred to as heliozincography but essentially the same process, known commercially as zinco, is the photographic process developed by Sir
Henry James
Henry James ( – ) was an American-British author. He is regarded as a key transitional figure between literary realism and literary modernism, and is considered by many to be among the greatest novelists in the English language. He was the ...
FRS (1803–1877) in the mid-nineteenth century.
This method enabled the accurate reproduction of images, manuscript text and outline engravings, which proved invaluable when originally used to create maps during the
Ordnance Survey
Ordnance Survey (OS) is the national mapping agency for Great Britain. The agency's name indicates its original military purpose (see ordnance and surveying), which was to map Scotland in the wake of the Jacobite rising of 1745. There was a ...
of Great Britain during the 1850s, carried out by the government's Topographical Department, headed by Colonel Sir Henry James.
Basis
The foundation of this method is the insolubility of
bichromate of potash upon exposure to light, allowing the printing of images on to
zinc
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
from
photographic negative
In photography, a negative is an image, usually on a strip or sheet of transparent plastic film, in which the lightest areas of the photographed subject appear darkest and the darkest areas appear lightest. This reversed order occurs because th ...
s.
Method
At this time, high-contrast negatives were made using the wet plate
collodion
Collodion is a flammable, syrupy solution of nitrocellulose in ether and alcohol. There are two basic types: flexible and non-flexible. The flexible type is often used as a surgical dressing or to hold dressings in place. When painted on the skin, ...
method (a solution of
nitrocellulose
Nitrocellulose (also known as cellulose nitrate, flash paper, flash cotton, guncotton, pyroxylin and flash string, depending on form) is a highly flammable compound formed by nitrating cellulose through exposure to a mixture of nitric acid and ...
in ether or acetone on glass). Once the negative had been made, a sheet of thin
tracing paper
Tracing paper is paper made to have low opacity, allowing light to pass through. It was originally developed for architects and design engineers to create drawings that could be copied precisely using the diazo copy process; it then found ma ...
was coated in a mixture of saturated potassium bichromate solution and gum water, and dried. This was then placed under the photographic negative and exposed to light for 2–3 minutes. The bichromate/gum mixture remained soluble on the parts of the tracing paper that were shielded from light by the opaque areas of the negative, allowing it to be removed, leaving an insoluble ‘positive’ image. This bichromate positive was then placed on a sheet of zinc covered in lithographic ink, and put through a
printing press
A printing press is a mechanical device for applying pressure to an inked surface resting upon a print medium (such as paper or cloth), thereby transferring the ink. It marked a dramatic improvement on earlier printing methods in which the ...
three or four times. After removal of the paper, the zinc plate was washed in a tray of hot water (containing a small amount of gum), using a
camel-hair brush to remove all the soluble bichromate combined with ink. What remained on the zinc plate was a perfect representation in ink of the original composition, by virtue of the ink binding to the insoluble potassium bichromate.
The main advantage and innovation of this process over lithography was the use of zinc plates rather than stone ones. Zinc plates were lighter and easier to transport, could produce more prints, and were far less brittle than the stone plates originally used. The use of zinc plates was also the origin of the name ''photozincography,'' which Sir Henry James claims to have invented.
History
![Domesday zinco Somerset Glastonbury](https://upload.wikimedia.org/wikipedia/commons/5/5f/Domesday_zinco_Somerset_Glastonbury.jpg)
Zinco or photozincography developed at the Ordnance Survey out of a need to reduce large-scale maps more effectively. The original method using a
pantograph
A pantograph (, from their original use for copying writing) is a mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a second pen. If a line dr ...
, was overcomplicated, time-consuming and, due to the number of moving parts, inaccurate. While there was some concern that photography would distort the image, Sir Henry set out to explore the possibility of using photography, setting up a photography department at the Ordnance Survey in 1855 and also securing funds to build the "glasshouse", a photography building with an all glass roof to allow as much natural light in as possible for photography. The development and discovery of photozincography or zinco came about four years later, being first mentioned in Sir Henry's report to
Parliament
In modern politics, and history, a parliament is a legislative body of government. Generally, a modern parliament has three functions: representing the electorate, making laws, and overseeing the government via hearings and inquiries. Th ...
in 1859.
While Sir Henry James claimed to have invented the process, a similar system of document copying had been developed in Australia.
John Walter Osborne
John Walter Osborne (20 February 1828 – 20 November 1902) was a chemist and engineer born in Ireland, who migrated to Victoria, Australia and in Melbourne pioneered the art of photo-lithography.
History
Osborne was born in Ireland, and recei ...
(1828–1902) developed a similar process and for the same reasons as Sir Henry, to avoid using the tracing system of the pantagraph. While developed at the same time Sir Henry's process, however as Sir Henry explained to a representative of Mr. Osborne in the quote below, he publicized it first.
I therefore handed this gentleman a copy of my Report, and desired him to read the account given of our process at page 6 of that Report, and to examine the copy of the Deed bound up with it, and not to show me the description of Mr. Osborne's process if it was differed from ours. After reading it, he said at once it was the same process, and I then told him it was useless for him to attempt to take out a patent as my printed Report had everywhere been circulated
Sir Henry, despite being the person who oversaw and set up the photography department, was not the actual inventor. The head of the photography department at Southampton, Captain A. de C. Scott, did much of the ground work and basic development on photozincography. Sir Henry did acknowledge the work of Scott in the development and use of the system in the introduction to the
photozincographied Domesday Book. Despite this it was Sir Henry who gained most of the public attention through his pamphlet on photozincography. He was knighted in 1861 for services to science.
The use of photozincography at the Ordnance Survey was a great success, with Sir Henry claiming it saved over £2000 a year, from the invention of photo-zincography; the cost of producing a map of a rural district was reduced from 4 to 1 and maps of towns were reduced from 9 to 1.
[The Photographic News Vol 3, 82, 30 March 1860, p360] It was also claimed that up to 2000 or 3000 impressions could be taken from a single plate. Despite this, the process was not perfect: it did not reproduce a full colour picture, and until 1875 boys were employed to colour in the maps produced by this method. The process, while better than the pantagraph, still required a large amount of labour to prepare the zinc plates for pressing. However, photozincography began to be used fairly rapidly in
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a subcontinent of Eurasia and it is located entirel ...
. Sir Henry was even honoured by the Queen of
Spain
, image_flag = Bandera de España.svg
, image_coat = Escudo de España (mazonado).svg
, national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond")
, national_anthem = (English: "Royal March")
, i ...
.
[Wakeman, ''Aspects of Victorian Lithography'', pp. 45, 49, 51.] Though originally developed to reproduce maps, the process was eventually to be used on a whole series of manuscripts, to preserve them and make them more available to the public. This included a
reproduction of Domesday Book in 1861–64 and several volumes of historical manuscripts. Whilst the process of photo-zincography was invented mostly for use the Ordnance Survey, The Photographic News stated that the process could also be used in the Patent office and would save vast amounts of time and money.
The use of photozincography began to decline in the 1880s as better methods of reproductions were made available and in the 1900s the glasshouse was pulled down to make way for new printing presses.
Gallery
Image: OS Map of Southampton new.jpg , An 1865 map showing the photography building and the Ordnance Survey offices
Image: PhotowithHJ.jpg , The photography building and Henry James
Image:Photographybuildingwithkids.jpg, A picture showing the photozincography building
See also
*
Anastatic lithography Anastatic lithography is a method of printing developed by 1840 in Erfurt. The technique provided a means for facsimile reproduction, which was developed and promoted by Werner and William Siemens
Sir Carl Wilhelm Siemens (4 April 1823 – 1 ...
*
Photography
Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employe ...
*
Gum bichromate
Gum bichromate is a 19th-century photographic printing process based on the light sensitivity of dichromates. It is capable of rendering painterly images from photographic negatives. Gum printing is traditionally a multi-layered printing process, ...
References
{{reflist
Photographic processes dating from the 19th century
Printmaking
Printing processes