Wednesday, February 27, 2013

Platinum Prints

...on the extreme margin of photographic subtlety
—George Bernard Shaw
Coming Home from the Marshes. Platinum Print by Peter Henry Emerson.
From Life and Landscape on the Norfolk Broads, 1886

Platinum prints, also known as Platinotypes, are produced by a monochrome printing process, most popular from 1880 to 1930, and known for providing the greatest tonal range of any printing method using chemical development.


Platinum prints are favored for their delicate and large tonal range, non-reflective surface quality, curl resistance and permanence.  
The magnification of a platinum print shows
the fibers through the emulsion layer

Tones range from warm black, to reddish brown, to expanded mid-tone grays unobtainable in silver prints.  Platinum (and/or palladium, it's sister element) lies on the paper surface, unlike silver printing processes where silver lies in a gelatin or albumen emulsion on top of the paper.  This makes the final image matte and the print curl resistant.  

While platinum prints are known for their superb image stability, one unique identifier is a positive image transfer created by paper degradation due to extended contact with a platinum print.  These transfer images are orange in appearance.  

Above: Image 1 is an undated cabinet card.  Image 2 is the same cabinet card with an
image transference on the back of the paper support.  Image 3 is the same as Image 2,
but digitally enhanced to show the transference effect more dramatically

History of the Process

One of the earliest observations of light rays on platinum were by Ferdinand Gehlem of Germany in 1830.  However, in 1844, Robert Hunt recorded the first known description of using platinum to create a print in his book Researchers on Light.  Although he tried many chemical combinations to refine the chemistry process, Hunt could not succeed in producing permanency in his images, most fading after a couple of months.  

Due to the rapid rise of other printing processes, such as salt and albumen printing, most photographers abandoned platinum printing until 1873 when the first patent for the
platinotype process was granted to William Willis.  He introduced the "hot bath" method where a mixture of ferric oxalate and potassium chloroplatinate are coated onto paper, which is exposed through a negative and developed in a warm solution of potassium oxalate.

Sea of Steps. Platinum Print by Frederick Evans, 1903.
While Willis had greatly advanced the chemistry of platinum printing, by 1880, there still was not reliable method for preparing platinum paper.  In 1882, Austrian Army officer, Giuseppe Pizzighelli patented a new process that made the commercial production of platinum paper viable for the first time.  The new process was briefly known as “Pizzitype” and was marketed under the name “Dr. Jacoby’s Printing Out Paper.”  

Willis quickly countered this advance by manufacturing a platinum paper designed for the cold-development process, which became the standard for the decade.  This process required the platinum to be placed in the sensitizing solution, and the paper coated with it.  His business called the Platinotype Company rapidly expanded and was soon selling paper across Europe and in the United States.  The Platinotype Company produced 15 types of platinum paper in various tones and surfaces, including smooth, semi-matte, and roughly textured.  Other companies, like the Eastman Kodak Company, produced platinum paper as well and a number of instruction manuals were published to aid amateurs in producing platinotypes.  

When Willis began marketing his paper, platinum was relatively cheap.  However, by 1907, platinum was 52 times more expensive than silver.  By 1916 a majority of manufacturers stopped producing platinum paper, and many photographers abandoned platinum printing for more economical alternatives.  However, a few photographers continue to use platinum printing to the present, popular as an "alternative," or non-silver, photographic technique.  

Three Roses by Tom Baril.
On the left is a Platinum Print and on the right is a Silver Print of the same image.
In the Platinum Print, the tones are more evenly distributed and give greater contrast and depth to the image.  Note the predominance of deeper hues and a shorter tonal range in the Silver Print. 


In photography, the palladiotype is a less-common variant of the platinotype.  The process came into greater use after World War I when platinum became too expensive.  Due to the rising cost and subsequent shortage of commercial paper, photographers replaced the platinum with cheaper palladium which gives similar effects.  However, compared to a true platinum print, a palladium print often gives slightly warmer tones, is easier to solarize, has deeper blacks and can produce a softer image with delicate highlights.  

The Chemical Process

Platinum printing is based on the light sensitivity of ferric oxalate.  Ferric oxalate is reduced to ferrous oxalate by UV-light only, creating greater exposure times than silver-based processes.  The ferrous oxalate then reacts with platinum (II) or palladium (II) reducing it to it's elemental form, which builds the image.  

By varying the amount of platinum/palladium and the addition of oxidizing chemicals such as hydrogen peroxide and potassium chlorate, the contrast and color of the final image can be modified.  Because of the non-uniformity of the coating and mixing processes, no two prints are exactly the same.  

The following video gives a great introduction to platinum printing and shows how the process is done today, blending traditional and modern techniques. 

References and Resources

No comments:

Post a Comment