Editing Platinum print (section)

{{Short description|Type of photographic print}}
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[[File:Coming Home from the Marshes, Peter Henry Emerson, 1886.jpg|upright=1.35|thumb|''Coming Home from the Marshes'', platinum print by [[Peter Henry Emerson]], 1886]]
{{Alternative photography}}
'''Platinum prints''', also called ''platinotypes'', are photographic prints made by a [[monochrome]] [[photographic printing|printing]] process involving [[platinum]].

Platinum tones range from warm black, to reddish brown, to expanded mid-tone grays{{Clarify|reason=The phrase "expanded mid-tone grays" is vague. Please explain what expanded means and in comparison to what.|date=April 2014}} that are unobtainable in silver prints.<ref>
{{cite web
 |url        =http://www.ellwoodcityledger.com/news/local_news/photographer-now-calls-former-fombell-post-office-home/article_81f71dcf-fd3d-5b2c-b267-31002eb483fb.html
 |title      =Photographer now calls former Fombell post office home
 |last       =Poole
 |first      =Eric
 |date       =2013-01-21
 |website    =ellwoodcityledger.com
 |publisher  =Ellwood City Ledger
 |access-date =2013-07-27
}}
</ref>{{Dubious|Comparison of platinum print vs silver-gelatin print tonality|reason=Please state which tones are unobtainable in silver prints. The referenced interview only suggests that "Platinum photo processing is still highly regarded from an artistic standpoint, Klimek said, because it captures the range of shades between black and white better than silver-based processing." but it does not speak of unobtainable tones. Further, this is not a precise statement.|date=April 2014}}

Unlike the [[Gelatin silver process|silver print process]], platinum lies on the paper surface, while [[silver]] lies in a [[gelatin]] or [[Albumen print|albumen]] [[emulsion]] that coats the paper. As a result, since no gelatin emulsion is used, the final platinum image is absolutely [[Paint sheen#Terminology|matte]] with a deposit of platinum (and/or [[palladium]], its sister element which is also used in most platinum photographs) absorbed slightly into the paper.<ref name="collectors-guide">{{cite web|url=http://www.collectorsguide.com/fa/fa031.shtml#RESOURCES |title=The Collector's Guide: Platinum Photography |publisher=Collectorsguide.com |date=2007-09-24 |access-date=2013-07-28}}</ref>

Platinum prints are the most durable of all photographic processes.{{Dubious|Durability|reason=Carbon prints are also claimed to be durable. Further, in the case of any prints, durability (or lack of) of the paper support should be mentioned.|date=April 2014}} The [[platinum group]] metals are very stable against chemical reactions that might degrade the print—even more stable than [[gold]]. It is estimated that a platinum image, properly made, can last thousands of years.<ref name="collectors-guide"/> Some of the desirable characteristics of a platinum print include:
* The reflective quality of the print is much more diffuse in nature compared to glossy prints that typically have [[Specular reflection|specular reflections]].
* A very delicate, large [[Dynamic range|tonal range]].
* Not being coated with gelatin, the prints do not exhibit the tendency to curl.
* The darkest possible tones in the prints are lighter than silver-based prints. Recent{{When|date=April 2014}} studies{{Citation needed|reason=DMax is not an optical illusion but an arguably complex, yet absolute measurement of reflectance. DMax of Se toned Ilford WT glossy paper reaches 2.4 which is close to theoretical maximum. Waxed platinum prints discussed on APUG.org quote DMax of 1.8, which is significantly less. It would be good to quote the studies referenced in this statement, especially if the effect is due to an illusion rather than measurable data.|date=April 2014}} have attributed this to an [[optical illusion]] produced by the gelatin coating on Resin Coated and fiber-based papers. However, platinotypes that have been waxed or varnished will produce images that appear to have greater maximum density than silver prints.
* A decreased{{quantify|reason=Statements of durability and permanence are not meaningful unless specific.|date=April 2014}} susceptibility to deterioration compared to silver-based prints due to the inherent stability of the process and also because they are commonly printed on 100% [[Cotton paper|rag papers]].
Many{{How many|date=April 2014}} practitioners have abandoned platinum and only use palladium.{{Citation needed|reason=Contemporary platinum prints are available for purchase from galleries, suggesting that this process has not been abandoned, therefore it would be helpful to quote some references to support the statement to the opposite.|date=April 2014}} The process using palladium alone ([[sodium tetrachloropalladate]]) is similar to standard processes, but rather than using [[ferric oxalate]] plus [[potassium chlorate]] as the restrainer (which is ineffective for palladium), a weak solution of [[sodium chloroplatinate]] is used instead.  Sodium chloroplatinate, in contrast to potassium chlorate, does not cause [[Film grain|grain]]. This formula is generally referred to as the ''Na2 method''. This somewhat misleading abbreviation was coined by Richard Sullivan of Bostick & Sullivan, one of the principal suppliers of chemistry and printing supplies, who popularized the process.