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Photographic paper

 
Photography Encyclopedia: photographic papers

The unique look of many vintage prints is due, in no small measure, to the wild profusion of paper types on which they were printed. Barnet Regal Rough and Verona De-Luxe; Dassonville Charcoal Black; Kosmos Vitegas; Buchet Stenox Gaslight; Criterion Vandyk; we shall not see their like again. For much of the 19th and 20th centuries, a bewildering variety of manufacturers offered a still more bewildering variety of papers in a range of weights (airmail, single, double, card), base colours (typically white, cream, and ivory), textures (from glossy through ‘pearl’ and matte to linen, silk, canvas, chamois, and more) and image tones (warm, cool, ‘engraving black’, red—the list went on).

Textures were varied by using additives (normally starch or silica) for matte effects or by impressing the paper or the emulsion or both with patterned rollers. Although albumen papers (invented in 1850) were popular in the early days, the vast majority of commercial papers have always been silver gelatin; the only other ready-coated material that has commonly been available is platinum, though there have intermittently been others.

Particularly in the 1970s and 1980s, papers became more and more alike, though in the 1990s warm-tone and to a lesser extent cool-tone papers revived in popularity. Image tones are partly a matter of crystal size, and partly a matter of ‘doping’ the emulsion with various additives. Unfortunately for photographers, though fortunately for the environment, cadmium was dropped as an ingredient, and the best warm-tone papers (such as Forte Polywarmtone) were never the same again. In some ways, those who bemoan the passing of the ‘good old days’ are, for once, right. On the other hand, there is much to praise in modern papers. Maximum blacks are for the most part much richer; development is much faster; and although the original variable-contrast (VC) papers were markedly inferior to single-contrast graded papers, in the 1980s the quality caught up and indeed surpassed the majority of graded papers. Ilford invented VC papers with Multigrade, though Du Pont was first to market with Varigam (using dyes supplied by Ilford) thanks to the Second World War.

There are also a few specialist papers that compare with the exotica of the past, for unusual surface textures and the like; leading manufacturers include Kentmere and Bergger. Many are graded rather than VC, sometimes for technical reasons (VC does not work well on canvas-textured papers, for example) and sometimes merely to pander to the prejudices of traditionalists.

The vast majority of modern papers are ‘projection speed’, i.e. suitable for enlargements, but there are still a few contact papers that are too slow for making enlargements; they can be handled under weak artificial light, hence their old name of ‘gaslight’ papers. For printing, they need strong UV sources, either a printing box or daylight. An even greater majority are ‘developing-out’ papers, in contradistinction to ‘printing-out’ papers where the paper darkens in direct proportion to the light falling on it. A typical printing-out paper takes anything from ten minutes to half an hour to form a usable image, which is then washed, toned, fixed, and washed again.

Historically, chloride papers were slow and cool toned, but gave the richest blacks; bromide papers were much faster and warmer, with lower maximum densities; and chlorobromides were predictably in between. Some also distinguished between chlorobromides (more chloride than bromide) and bromochlorides (more bromide than chloride). Today, the distinctions between bromide and chlorobromide/bromochloride no longer hold good: advances in crystal technology mean that chlorobromides can be warmer than bromides, and maximum densities are independent of halide type.

There is a popular myth that the more silver a paper has, the richer the tonality. This is not borne out in practice. Beyond a certain point, obviously, there can be no increase in maximum density, and there is no point in using more silver. Actual coating weights vary from under 1 gram per square metre (gsm) to over 2 gsm. Most manufacturers use 1.6 to 1.8 gsm for projection (enlarging) papers, but a contact paper can use as little as 0.9 gsm and still produce a better maximum black than a projection paper with twice the coating weight: the secret lies in the smaller crystal size of the slower paper.

There is also a widespread and substantially irrational prejudice against resin-coated (RC) papers. As with VC papers, early RC papers were markedly inferior to fibre base (FB), with poor maximum blacks, an unpleasant ‘bloom’, and a tendency to cracking and crazing; but today, if the print is behind glass, it is often impossible to distinguish between RC and FB. There is probably a small archival advantage in FB papers, however, and for ‘fine-art’ purposes (where the tactile advantages are also important) FB continues to rule the roost.

For reproduction, glossy prints should be the automatic choice—textured papers often reproduce very badly indeed—and there is little or no reason not to use RC paper. For exhibition, the photographer's taste must reign supreme, though matte and textured prints are easier to light and therefore often easier to see.

Although much can be quantified about papers, including their speed and contrast under specified conditions, the final results that they deliver in different photographer's hands argue strongly that printing is more akin to cookery or perhaps alchemy than to science. Developers play a very major part in both image tone (warm or cool) and contrast (a developer can increase effective contrast by up to half a grade, or decrease it by a grade or more), but enlarger type, negative characteristic curve, and more can mean that a paper which delivers superb results for one photographer can be a disaster for another, and of course vice versa.

A note on formats: papers were originally sold in large sheets, to be cut by the user, but by 1900 pre-cut paper was widely available in a huge range of sizes, as it is to this day; although, paradoxically, the ‘halvable’ DIN A-series, the most logical size of all, has never become popular. At least as curiously, the popular 20.3 × 25.4 cm (8 × 10 in) size is a poor match for 35 mm, but 20.3 × 30.5 cm (8 × 12 in) paper (which would be far more useful) has never been a standard size.

— Roger W. Hicks

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WordNet: photographic paper
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Note: click on a word meaning below to see its connections and related words.

The noun has one meaning:

Meaning #1: light-sensitive paper on which photograph can be printed
  Synonym: photographic material


Wikipedia: Photographic paper
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This article is about light-sensitive photographic media; for digital printing media please see Photo printer, photo paper and inkjet paper.

Photographic paper is paper coated with light-sensitive chemicals, used for making photographic prints.

Photographic paper is exposed to light in a controlled manner, either by placing a negative in contact with the paper directly to produce a contact print, by using an enlarger in order to create a latent image, by exposing in some types of camera to produce a photographic negative, or by placing objects upon it to produce photograms. Photographic papers are subsequently developed using the gelatin-silver process to create a visible image.

Contents

History

The effect of light in darkening a prepared paper was discovered by M. Charles in 1800 or by Thomas Wedgwood in 1802.[1]

Photographic papers have been used since the beginning of all negative–positive photographic processes as developed and popularised by William Fox Talbot (Great Britain/1841-calotype).

Traditional photographic papers are still sold commercially today.

Types of photographic papers

Photopapers 1.jpg

Photographic papers fall into one of three sub-categories:

Papers used for negative-positive processes. This includes all current black and white papers and chromogenic colour papers.

Papers used for positive-positive processes in which the "film" is the same as the final image (e.g. the Polaroid process).

Papers used for positive-positive film-to-paper processes where a positive image is enlarged and copied onto a photographic paper, for example the Ilfochrome process.

Structure

All photographic papers consist of a light-sensitive emulsion, consisting of silver halide salts suspended in a colloidal material - usually gelatin- coated onto a paper, resin coated paper or polyester support.

In black and white papers, the emulsion is normally sensitised to blue and green light, but is insensitive to wavelengths longer than 600nm in order to facilitate handling under red or orange safelighting. [2]

In Chromogenic colour papers, the emulsion layers are sensitive to red, green and blue light, respectively producing cyan, magenta and yellow dye during processing.

Base materials

Black-and-white papers

Modern black-and-white papers are coated on a small range of bases; baryta-coated paper, resin-coated paper or polyester. In the past, linen has been used as a base material. [3]

Fibre-based papers (FB)

Fibre-based (FB or Baryta) photographic papers consist of a paper base coated with a baryta. Tints are sometimes added to the baryta to add subtle colour to the final print; however most modern papers use optical brighteners to extend the paper's tonal range.[3]

Most fibre-based papers include a clear hardened gelatin layer above the emulsion which protects it from physical damage, especially during processing. This is called a supercoating. Papers without a supercoating are suitable for use with the bromoil process. [2]

Fibre-based papers are generally chosen as a medium for high-quality prints for exhibition, display and archiving purposes. These papers require careful processing and handling, especially when wet. However, they are easier to tone, hand-colour and retouch than resin-coated equivalents. [3]

Resin-coated papers (RC)

The paper base of resin-coated papers is sealed by two polyethylene layers, making it impenetrable to liquids. Since no chemicals or water are absorbed into the paper base, the time needed for processing, washing and drying durations are significantly reduced in comparison to fibre-based papers. Resin paper prints can be finished and dried within twenty to thirty minutes. Resin-coated papers have improved dimensional stability, and do not curl upon drying. [3]

Colour papers

All colour photographic materials available today are coated on either RC (resin coated) paper or on solid polyester. The photographic emulsion used for colour photographic materials consists of three colour emulsion layers (cyan, yellow and magenta) along with other supporting layers. The colour layers are sensitised to their corresponding colours. Although it is commonly believed that the layers in negative papers are shielded against the intrusion of light of a different wavelength than the actual layer by colour filters which dissolve during processing, this is not so. The color layers in negative papers are actually produced to have speeds which increase from cyan (red sensitive) to magenta (green sensitive) to yellow (blue sensitive), and thus when filtered during printing, the blue light is "normalized" so that there is no crosstalk. Therefore the yellow (blue sensitive) layer is nearly ISO 100 while the cyan (red) layer is about ISO 25. After adding enough yellow filtration to make a neutral, the blue sensitivity of the slow cyan layer is "lost".[citation needed]

In negative-positive print systems, the blue sensitive layer is on the bottom, and the cyan layer is on the top. This is the reverse of the usual layer order in color films.[citation needed]

The emulsion layers can include the colour dyes, as in Ilfochrome); or they can include colour couplers, which react with colour developers to produce colour dyes, as in type C prints or chromogenic negative–positive prints. Type R prints, which are no longer made, were positive–positive chromogenic prints.[citation needed]

Black and White emulsion types

The emulsion contains light sensitive silver halide crystals suspended in gelatin. Black and white papers typically use relatively insensitive emulsions composed of silver bromide, silver chloride or a combination of both. The silver halide used affects the paper's sensitivity and the image tone of the resulting print.[2]

Chloride papers

Popular in the past, chloride papers are nowadays unusual; a single manufacturer produces this material. [4] These insensitive papers are suitable for contact printing, and yield warm toned images by development. Chloride emulsions are also used for printing-out papers, or POP, which require no further development after exposure. [5]

Chlorobromide papers

Containing a blend of silver chloride and silver bromide salts, these emulsions produce papers sensitive enough to be used for enlarging. They produce warm-black to neutral image tones by development, which can be varied by using different developers.[3]

Bromide papers

Papers with pure silver bromide emulsions are sensitive and produce neutral black or 'cold' blue-black image tones.[2]

Contrast control

Fixed grade - or graded - black-and-white papers were historically available in a wide range of contrast grades, numbered 0 to 5, with 0 being the softest, or least contrasty paper grade and 5 being the hardest, or most contrasty paper grade. Low contrast negatives can be corrected by printing on a contrasty paper; conversely a very contrasty negative can be printed on a low contrast paper. [2] Because of decreased demand, most extreme paper grades are now discontinued, and the few graded ranges still available include only middle contrast grades.[5]

Variable-contrast - or "VC" papers - account for the great majority of consumption of these papers in the 21'st century. VC papers permit the selection of a wide range of contrast grades, in the case of the brand leader between 00 and 5. These papers are coated with a mixture of three emulsions, all of equal contrast and sensitivity to blue light. However, each emulsion is sensitised in different proportions to green light. Upon exposure to blue light, all emulsions act in an additive manner to produce a high contrast image. When exposed to green light alone, the emulsions produce a low contrast image because each is differently sensitised to green. By varying the ratio of blue to green light, the contrast of the print can be continuously varied between these extremes, creating all contrast grades from 00 to 5. Filters in the enlarger's light path are a common method of achieving this control. Magenta filters absorb green and transmit blue and red, while yellow filters absorb blue and transmit green and red. [6]

The contrast of photographic papers can also be controlled during processing or by the use of bleaches or toners.[citation needed]

Archival stability

The longevity of any photographic print media will depend upon the processing, display and storage conditions of the print.

Black-and-white prints

Fixing must be effective. It is essential that all non-image silver is converted into soluble silver compounds that can be removed by later washing.

Washing must remove all soluble silver compounds and all residual fixing chemicals and their products from the emulsion and paper base.

Toning should convert the remaining silver into more stable compounds. Commonly used archival toners are: selenium, gold and sulphide.

Prints on fibre-based papers that have been properly fixed and well washed should last at least fifty years without fading. Some alternative (non-silver) processes - such as platinum prints - employ metals that are, if processed correctly, inherently more stable than gelatin-silver prints.[2]

Colour prints

For color images, Ilfochrome is often used because of its clarity and the stability of the colour dyes.[citation needed]

Standard print sizes

See also

References

  1. ^ Sydney Smith, Francis Jeffrey Jeffrey, Macvey Napier, William Empson, George Cornewall (1843). The Edinburgh Review. London: Longman, Orme, Brown, Green, and Longmans; and Edinburgh: Adam and Charles Black. http://books.google.com/books?id=9-sEAAAAQAAJ&pg=PA335&dq=talbot+%22photographic+paper%22&lr=&as_brr=1&ei=vM5BSOy2C4_aigHHy7iIBQ#PPA313,M1. 
  2. ^ a b c d e f Sowerby (ed.), A.L.M. (1961 (19th Ed.)), Dictionary of Photography: A Reference Book for Amateur and Professional Photographers, London: Illife Books Ltd. 
  3. ^ a b c d e Langford, Michael (2000 (7th Ed.)). Basic Photography. Oxford, England.: Focal Press. ISBN 0 240 51592 7. 
  4. ^ Chamlee, Paula; Smith, Michael A. (2008), http://www.michaelandpaula.com/mp/newpaper.html, retrieved 2008-10-03 
  5. ^ a b Reed, Martin (1998;2004), http://www.silverprint.co.uk/info/yespap.html, retrieved 2008-10-03 
  6. ^ Ilford Imaging UK LTD. (December 2001) (PDF), Contrast Control for Ilford Multigrade Variable Contrast Papers, http://www.ilfordphoto.com/download.asp?n=29&f=2006130201152306.pdf, retrieved 2008-10-03 

 
 

 

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Photography Encyclopedia. The Oxford Companion to the Photograph. Copyright © 2005 by Oxford University Press. All rights reserved.  Read more
WordNet. WordNet 1.7.1 Copyright © 2001 by Princeton University. All rights reserved.  Read more
Wikipedia. This article is licensed under the Creative Commons Attribution/Share-Alike License. It uses material from the Wikipedia article "Photographic paper" Read more