Platinum print
Platinum tones range from warm black, to reddish brown, to expanded mid-tone grays[clarification needed] that are unobtainable in silver prints.
[3] In 1832, Englishmen Sir John Herschel and 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 print.
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 to a positive image, eventually becoming permanent.
2011, June 8, 1873),[3] and again in 1878 and 1880, which he leveraged to gain commercial success in the manufacture of platinum papers sold through his Platinotype Company for professional and amateur use.
Two years, later two Austrian Army officers, Giuseppe Pizzighelli and Arthur Baron V. Hubl, published a dissertation describing a straightforward process for preparing the paper.
They continued their research for several years, and in 1887, Pizzighelli patented a new process that made the commercial production of platinum paper viable for the first time.
Four years later, Willis began manufacturing a platinum paper that was designed for the cold-bath process, and this became the standard for the rest of the decade.
The business he started in 1880, called the Platinotype Company, rapidly expanded, and soon he was selling his paper throughout Europe and in the United States.
Kodak instead bought the relatively new company of Joseph Di Nunzio who had recently developed his own brand of platinum paper comparable to Willis's, which he sold under the name of "Angelo".
Penn had spent his career up to that point making photographs that were seen almost exclusively in reproduction within the glossy pages of magazines and in his pivotal 1960 book Moments Preserved.
Penn set himself the challenge of producing photographic prints that would surpass the technical limitations of reprographic media and deliver a deeper visual experience.
He was drawn to the antiquated platinum process for its long grayscale – its ability to display a seemingly infinite array of gradations between pure white and absolute black.
Penn solved the problem of aligning and re-aligning the negative and the print surface over multiple exposures by borrowing a technique from the graphic arts: he mounted his paper on a sheet of aluminum with a series of registration guides along the top edge.
In 2002, working from research done by Howard Efner and Richard Sullivan, Dick Arentz formulated the methodology for using sodium chloroplatinate as a contrast control agent.
When minute quantities of sodium chloroplatinate are added to the palladium salt/ferric oxalate emulsion it produces the high-contrast prints needed for thin negatives, but does not exhibit the granularity found when using traditional chlorates.
Many artists achieve varying effects by choosing different papers for different surface characteristics, including vellum, 100% cotton rag, silk, and rice, among others.
