Editing Platinum print (section)

== History ==
The first person to have recorded observing the action of light rays on platinum was [[Ferdinand Gehlen]] of Germany in 1830. The following year, his countryman, [[Johann Wolfgang Döbereiner|Johann Wolfgang Dobereiner]], determined that the action of light on platinum was quite weak, but that perhaps something could be combined with platinum to increase its sensitivity. Through experimentation, he eventually found that [[ferric oxalate]] was a highly-effective enhancer. The combination of these two metals remains the basis of the platinotype process in use today.<ref name="TPP">John Hafey & Tom Shillea. [https://web.archive.org/web/20131228084318/http://www.kimeia.com/pdf/history.pdf The Platinum Print & The History of the Platinum Process]. kimeia.com</ref>

In 1832, Englishmen [[John Herschel|Sir John Herschel]] and [[Robert Hunt (scientist)|Robert Hunt]] conducted their own experiments, further refining the chemistry of the process. In 1844, in his book ''[[Researches on Light]]'', Hunt recorded the first known description of anyone employing platinum to make a [[Photographic printing|photographic print]]. However, although he tried several different combinations of chemicals with platinum, none of them succeeded in producing any permanency in the image. All of his prints faded after several months.

Over the next decade, Hunt noted that platinum prints he had left in the dark faded very slowly but gradually resumed their original density, and had also shifted from a [[Negative (photography)|negative]] to a [[Positive (photography)|positive image]], eventually becoming permanent.<ref name=TPP />

By the early 1850s, however, other more reliable photographic processes, such as [[salt print|salt]] and [[albumen print|albumen]] printing, had been developed and were beginning to be widely used. Those scientists who had previously conducted research on platinum lost interest in the process as other methods became more commercially viable. The only major advances in platinum research reported during that decade were made independently by [[C.J. Burnett]] and Lyonel Clark of Great Britain. In 1859, Burnett published an article in the ''[[British Journal of Photography]]'' describing his use of sodium chloroplatinate as a [[fixing agent]]. His modification of the platinum printing process resulted in prints that were permanent enough that he could exhibit them in public. That same year, Clark also exhibited prints made using a slightly different process.<ref name="TPP" />