 | This articleneeds additional citations forverification. Please helpimprove this article byadding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Photographic print toning" – news ·newspapers ·books ·scholar ·JSTOR(September 2008) (Learn how and when to remove this message) |
.jpg)
| Alternative photography |
|---|
 |
Inphotography,toning is a method of altering the color ofblack-and-white photographs. Inanalog photography, it is a chemical process carried out on metal salt-basedprints, such as silver prints, iron-based prints (cyanotype orVan Dyke brown), orplatinum orpalladium prints. Thisdarkroom process cannot be performed with a color photograph. The effects of this process can be emulated with software indigital photography. Sepia is considered a form of black-and-white ormonochrome photography.
Most toners work by replacing the metallicsilver in theemulsion with a silver compound, such assilver sulfide (Ag2S) in the case of sepia toning. The compound may be more stable than metallic silver and may also have a different color or tone. Different toning processes give different colors to the final print. In some cases, the printer may choose to tone some parts of a print more than others.[1]
Toner also can increase the range of shades visible in a print without reducing the contrast.Selenium toning is especially effective in this regard. Some toning processes can improve the chemical stability of the print, increasing its potential longevity. Other toning processes, such as those including iron and copper, can make the print less stable. Many chemical toners are highly toxic, some even containing chemicals that arecarcinogenic. It is therefore extremely important that the chemicals be used in a well ventilated area, andrubber gloves and face protection should be worn when handling them.
Selenium toning is a popular archival toning process, converting metallic silver tosilver selenide. In a diluted toning solution, selenium toning gives a red-brown tone, while a strong solution gives a purple-brown tone. The change in color depends upon the chemical make-up of the photographic emulsion being toned.Chloro-bromide papers change dramatically, whilst purebromide papers change little. Fibre-based papers are more responsive to selenium toning.[2]
Selenium toning may not produce prints quite as stable assepia orgold toning. Recently, doubts have surfaced as to the effectiveness of selenium toner in ensuring print longevity.[3]
Sepia toning is a specialized treatment to give ablack-and-white photographic print a warmer tone and to enhance its archival qualities. Themetallic silver in the print is converted to asulfide compound, which is much more resistant to the effects of environmental pollutants such as atmospheric sulfur compounds.Silver sulfide is at least 50% more stable than silver.[4]
There are three types of sepia toner in modern use:
Except for polysulfide toners, sepia toning is done in three stages. The print is first soaked in apotassium ferricyanide bleach to reconvert the metallic silver tosilver halide. The print is washed to remove excess potassium ferricyanide and then immersed into a bath of toner, which converts the silver halides to silver sulfide.
Incomplete bleaching creates a multi-toned image with sepia highlights and gray mid-tones and shadows. This is calledsplit toning. The untoned silver in the print can be treated with a different toner, such asgold orselenium.[5]
Fred JudgeFRPS made extensive use of sepia toning for postcards produced by the British picture postcards manufacturerJudges Postcards.
Metal replacement toners replace the metallic silver, through a series of chemical reactions, with aferrocyanide salt of atransition metal. Some metals, such asplatinum orgold, can protect the image. Others, such asiron (blue toner) orcopper (red toner), may reduce the life of the image.[citation needed]
Metal-replacement toning with gold alone results in a blue-black tone. It is often combined with a sepia toner to produce a more attractive orange-red tone. The archival Gold Protective Solution (GP-1) formula uses a 1% gold chloride stock solution with sodium or potassium thiocyanate.[6] It is sometimes used to split tone photographs previously toned in selenium for artistic purposes.[7]
Dye toners replace the metallic silver with adye. The image will have a reduced lifetime compared with an ordinary silver print.[citation needed]
Toning can be simulated digitally, either in-camera or inpost-processing. The in-camera effect, as well as beginner tutorials given for software likePhotoshop orGIMP, use a simple tint. More sophisticatedsoftware tends to implement sepia tones using theduotone feature. Simpler photo-editing software usually has an option to sepia-tone an image in one step.
The examples below show a digital color photograph, a black-and-white version and a sepia-toned version.
The following are examples of the three types using film:
Chemical toning (formulas and technique):
Digital "toning":
Color topics | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Color science |
|  | ||||||||
| Color philosophy |
| |||||||||
| Color terms |
| |||||||||
| Color organizations | ||||||||||
| Names |
| |||||||||
| Related | ||||||||||
