by Gerald Boerner

  

JerryPhoto_8x8_P1010031 In yesterday’s posting, we discussed the platinum/palladium printing process in general, semi-theoretical terms. Today, we take a more focused look at the mechanics of the process. Unlike the printing-out processes used with salt prints, albumen prints, and collodion prints, the platinum process requires more than just processing the print through water washes and then, in all probability, toning them. These chemicals are relatively mild and non-toxic, except for the heavy metals used in the toning.

Platinum prints, on the other hand, use a developing-out process that employs several solutions that are toxic. The photographer is recommended to wear gloves and exercise caution while processing. The heavy metals used to coat the paper, develop the image and process the finished print are much more complicated and “tricky.”

The process introduces variables at every stage of the process. Mixing the solutions may vary. The coating of the paper and the choice of the paper itself can produce variations. The developing techniques and consistency from one development to the next can cause the outcome to differ. This is the reason behind the unique appearance of platinum prints from one photographer to the next.

We hope that the following will provide you with a methodological overview of platinum printing. After reading this overview, you should read the complete references for the fuller details before attempting this process on your own.  GLB

    

“Twelve significant photographs in any one year is a good crop.”
— Ansel Adams

“While photographs may not lie, liars may photograph.”
— Lewis Hine

“Travel becomes a strategy for accumulating photographs.”
— Susan Sontag

“There’s a discipline. When you take someone’s portrait, you don’t have to take 50 photographs, just find that one so that when you release the shutter, that’s the image that you took.”
— Matthew Modine

“There’s no question that photographs communicate more instantly and powerfully than words do, but if you want to communicate a complex concept clearly, you need words, too.”
— Galen Rowell

“To take a photograph is to participate in another person’s mortality, vulnerability, mutability. Precisely by slicing out this moment and freezing it, all photographs testify to time’s relentless melt.”
— Susan Sontag

“We must carefully consider card security solutions, such as adding photographs or machine-readable electronic strips, so to prevent further breaches of individual privacy that could result from changes to the design of Social Security Cards.”
— Ron Lewis

“To take photographs means to recognize – simultaneously and within a fraction of a second – both the fact itself and the rigorous organization of visually perceived forms that give it meaning. It is putting one’s head, one’s eye and one’s heart on the same axis.”
— Henri Cartier-Bresson

  

Note:
This posting is intended for the educational use of photographers and photography students and complies with the “educational fair use” provisions of copyright law. For readers who might wish to reuse some of these images should check out their compliance with copyright limitations that might apply to that use.

GLB

  

Early Photographic Technique: Platinum Print Processing

Door_and_Bookshelf Platinum prints, also called platinotypes, are photographic prints made by a monochrome printing process that provides the greatest tonal range of any printing method using chemical development.

Unlike the silver print process, platinum lies on the paper surface, while silver lies in a gelatin or albumen emulsion that coats the paper. As a result, since no gelatin emulsion is used, the final platinum image is absolutely 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.

No notable advances were made during the 1860s, no doubt due to the rapid rise in the popularity of other processes. It was 1873 before the first patent for a platinotype process was granted, to William Willis (British Patent No. 2011, June 8, 1873). Willis introduced the "hot bath" method where a mixture of ferric oxalate and potassium chloroplatinate are coated onto paper which is then exposed through a negative and developed in a warm solution of potassium oxalate. This is the basic platinotype process which is in use today. In 1878 Willis was granted a second patent for a simplification of his initial process that eliminated the need for a hyposulfate (metabisulfate) bath. Two years later he received a third patent for further refinements to the process.

While Willis had greatly advanced the chemistry of the platinum process, by 1880 there was still no reliable method for the individual preparation of platinum paper. Two years later two Austrian Army offices, 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. The new process was briefly known as a "Pizzitype" and was marketed under the name "Dr. Jacoby’s Printing Out Paper."

Willis quickly countered this advance by obtaining two more patents in 1888 for cold-bath processes. By adding more platinum to the developing process, he produced prints that had dense brown-black shadows rather than the lighter browns that were the best previous processes could produce. While much more aesthetically pleasing, prints developed by this process were difficult to reliably produce.

Four years later he 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 By 1906 his company had sales totaling US $273,715 ($6,510,362 in 2009 dollars), a significant amount at that time.

The Platino-Palladiotype Process

The following method of printing in platinum, palladium, or a mixture of both metals, has been evolved to overcome the difficulties and disadvantages of the traditional platinotype. Newcomers are strongly advised to begin with palladium alone – even though it is at present as expensive as platinum: palladium more readily gives a finer image on a wider range of papers. Its permanence is, for all practical purposes, hardly less than that of platinum.

Always be careful when handling chemicals. Read the health and safety instructions.

This method is a printing-out process, unlike traditional platinotype which requires development. The sensitized paper acquires a controlled degree of humidity, which allows formation of the platinum-palladium image during the exposure – a process that can easily be monitored, making test-strips unnecessary.

For those who have no experience of Iron printing please check out the article Preparations to Alternative Printing that explains what you need and how to prepare for the processing.

The printing-out process has a self-masking effect, which accommodates a wide range of negative density.

Chemicals required for the Sensitizers:
  • Ammonium Iron(III) Oxalate 30g
  • Ammonium Tetrachloroplatinate(II) 5g
  • Ammonium Chloride 1.8g
  • Palladium(II) Chloride 3g

GPR reagent grade is adequate in all cases.

Making up the Sensitizer Solutions

mw_pt1_kit The sensitizer is prepared by mixing the iron solution with an equal volume of either the palladium solution or the platinum solution, or, for a mixed-metal print, a combination of both. It is not advisable to store large quantities of the ammonium tetrachloroplatinate(II) solution, which tends to decompose with time. The instructions below are scaled to realistic quantities, which should suffice to make about 60 10x8in platinum-palladium prints.

The iron solution (Fe) contains the salt Ammonium Iron(III) Oxalate at a concentration of 60% w/v. This substance is also known as Ferric Ammonium Oxalate, or Ammonium Ferrioxalate, formula (NH4)3[Fe(C2O4)3].3H2O.

To make up
  1. Dissolve 30g Ammonium Iron(III) Oxalate in 30cc of warm (about 50°C) distilled water with stirring.
  2. Make up to a final volume of 50cc with distilled water at room temperature.
  3. Filter (Whatman #1 paper, is adequate).
  4. Store in a brown bottle at room temperature in the dark. This solution keeps indefinitely.

The palladium solution (Pd) contains Ammonium Tetrachloropalladate(II), formula (NH4)2[PdCl4], at a concentration of 20% w/v. The solution can simply be made by dissolving 5g of this substance in distilled water and making up to 25cc. However, the following method is less expensive.

To make up:
  1. Dissolve 1.8g Ammonium Chloride in about 20cc of hot (70-80 °C) distilled water.
  2. Add 3g Palladium(II) Chloride with stirring (which should be well-powdered. HAZARD: wear a dust mask).
  3. Keep hot, stirring occasionally, until all has dissolved (about an hour).
  4. Make up to 25cc with distilled water. Filter and bottle when cool. This solution keeps indefinitely.

The platinum solution (Pt) contains Ammonium Tetrachloroplatinate(II), at a concentration of 25% w/v. This substance used to be called Ammonium Chloroplatinite, formula (NH4)2[PtCl4].

To make up:
  1. Dissolve 5g Ammonium Tetrachloroplatinate(II) in 15cc of distilled water at room temperature.
  2. Make up to 20cc with distilled water.
  3. Filter or decant off any small amount of yellow solid formed, and bottle immediately, avoiding unnecessary exposure to the air. This solution should keep for six months or so.
  4. NB. Allow this solution to stand for at least 24 hours before first use.
Chemicals required for the Processing Solutions

Three solutions are required:

  • Ethylenediaminetetraacetic acid disodium salt
  • Ethylenediaminetetraacetic acid tetrasodium salt
  • Kodak ‘Hypoclear’ powder, or sodium sulphite
Making up the Processing Solutions

mw_pt2_bottles The wet-processing procedure uses solutions of the sodium salts of ethylenediaminetetraacetic acid – otherwise known as EDTA.

Two separate clearing baths, each of strength about 5% w/v, are recommended: dissolve ca. 50g of the solid in each litre of water at room temperature.

The first bath is of disodium EDTA, with an acidic pH around 3 to 4, which is optimum for complexing iron(III) and is acid enough to avoid hydrolysis leading to yellow iron stains; the capacity of a one-litre bath will be about 50 10x8in prints.

Clearing of the residual iron compounds from the paper is improved by immersion next in a bath of Kodak Hypoclearing Agent at working strength; the inorganic sulphite in this tends to reduce any residual iron(III) to iron(II) which is then removed in the final tetrasodium EDTA bath; these last two baths have an alkaline pH (around 9) which is optimum for complexation of iron(II) and leaves the paper in a beneficial alkaline condition.

The wet-processing sequence
  • Mixing the Sensitizer…
    Solutions should be mixed at room temperature under tungsten lighting.
  • Rod-coating… 
    All manipulation of the sensitized paper can be carried out under moderate tungsten lighting, but you should avoid fluorescent light or daylight.
  • Drying…
    After coating, allow the sensitized paper to rest horizontally at room temperature until its surface sheen has disappeared.
  • Storage…
    The sensitized paper is best used within a few hours.
  • Humidifying…
    The key to the printing-out process lies in controlling the humidity of the sensitized paper just before exposure.
  • Making the Exposure…
    Interpose a protective polyester film between paper and negative if you think it advisable.
Control of Print Contrast

There is no substitute for making the negatives correctly in the first place. Having prepared a negative of approximately the right density range (about 2), the contrast may be fine-tuned in the printing process by two main controls.

These controls include:

  • The choice of platinum: palladium ratio
  • The RH of the sensitized paper before exposure

8_Shaniko_School Platinum and palladium sensitizers differ in the contrast and colour of print they produce: palladium yields the warmer tones and a softer image (i.e. a longer printing exposure range) with greater delicacy in the high values. This provides a useful control, because the platinum and palladium solutions can be combined in any ratio in the sensitizer to fulfill your wishes for the finished print. However the two metals print out with different speeds, palladium being the faster by a factor of about two. A mixed print will therefore not contain the two metals in the same ratio as in the sensitizer, but will be depleted in platinum.

Control of Print Colour

There are several factors that influence the colour of a platinum-palladium print, which can range from gingery-brown to bluish-black.

This is an area for experiment and personal taste:

  • Lower RH on exposure tends to produce browner tones.
  • Palladium yields warmer tones than platinum.
  • With pure palladium, gelatine-sized papers yield warmer tones than Aquapel(tm)- or starch-sized papers.

Getting Started with Platinum Printing

Big Negatives

Platinum prints (and most other alternative processe prints) are contact prints. That means the negative is in direct contact with the printing paper and the final print is the same size as the negative.  You cannot make a platinum print with an enlarger.  (Sorry. It just won’t happen. More on that later.)  So, how do you get a big negative?  There are three basic processes available to create a large negative. The first method is an in-camera negative. You now have a reason to buy that 8 x 10 (or larger) view camera.  The second is to create copy negatives using traditional wet process technology. This involves making a film positive using an enlarger and then contact printing the enlarged positive to another piece of film to get a large negative for contact printing.

At one time a large American Photographic Products company made direct copy film that eliminated the film positive step of the process.  I am not sure if that product is still available. The last method for creating an enlarged negative is described in Dan Burkholder’s book, Digital Negatives for Contact Printing.  It describes the methods for using scanners, computers, desktop printers or pre-press service providers to create enlarged negatives for contact.  If you are going to pursue this method of making enlarged negatives, this gets you just about all the way there.

Printing

A_Boy_s_Song You will need some device to hold the negative in contact with the printing paper.  The goal is to keep the negative and paper in direct contact for the duration of the exposure.  There are multiple ways of accomplishing this. It can be as simple as taping two sheets of glass with a duct tape hinge or as complicated as a vacuum printing frame.  There is no doubt that the “glass sandwich” from your local glazier is the least expensive solution that works as a printing frame. I used one for about ten years printing 5 x 7 and 8 x 10 in-camera negatives. If you use copy film, or lithographic film, then you should use either a spring back contact or vacuum printing frame because of the thin base used in those films. 

These thin films need the mechanical force of a spring or vacuum to hold the film tightly to the paper. If the film is not held tightly against the paper, the results will be disappointing because the print will either be out of focus or show Newton’s rings.  There is no doubt a vacuum printing frame is the best gear for contact printing.  If you are a careful shopper the cost of a 17 x 22 used vacuum easel is probably less than the cost of a brand new spring back contact printing frame.

Light Source

Alternative processes are sensitive to UV light. That’s why an enlarger for alternative processes won’t work. You can’t see to focus with invisible UV light.  Exposure times can also be very long. I have had contact prints that require 45 or 50 minute exposures.  Most of my print exposures are between 6 and 12 minutes.  Get out your calculator to do the inverse square calculation for enlarging time when the light source is a few feet rather than a few inches from the paper. It would be economically (and physically) impractical to build a UV enlarger.

There are two sources of UV light. One is a bank of light bulbs specifically designed to produce UV light and the other is sunlight. UV light sources can be high intensity lights used in the graphic arts industries, or fluorescent UV lights.  Banks of fluorescent UV light bulbs are the most common way to print alternative processes. These UV light sources can be purchased, or they can be made at home. If you have some skills with carpentry and electrical wiring, you can build a light box yourself. Plans exist for this type of construction in several alternative process handbooks. The electrical components of a UV light box are the majority of the cost of the unit.  A Do It Yourself project won’t save you fifty per-cent of the price of a new purchased UV unit. 

Sunlight is the other source of UV light for platinum printers.  Sunlight is still available today (depending on where you live) and the price is right.  The only drawback to sun printing is it takes more than a few failures to be able to accurately gauge the provisional image formed during exposure so that the developed image is correctly exposed.  Most photographers opt for the UV bulbs. 

Miscellaneous Supplies

We’ve almost completely set up the darkroom. The only things left are the trays and utensils. No metal is allowed because metal contamination will play havoc with platinum printing.  You will need to get new trays, chemical storage jugs and anything else that will touch the paper during processing. It is not necessary to get a new print washer or drying screens, but everything else must be brand new. Thank goodness these last items are not very expensive.  That’s a good thing because now we are really going to spend some money.

Making your own Printing Paper

Platinum printing is the ultimate in printing flexibility. This flexibility is achieved through the photographer’s selection of paper (with many choices for weight, surface and color), contrast level and print tone. Once these selections are made the emulsion is hand-coated on the paper.

There are a number of excellent detailed descriptions of the platinum printing process available either on-line or in book form. The platinum print is created by UV light converting Ferric oxalate it to its ferrous state. Platinum salts bond to the iron during this process.  When developed out, platinum salts are reduced to metallic platinum to create the image.  Residual iron is removed in a series of fixing baths leaving an image of metallic platinum embedded in paper. (This embedding of the image in the paper is one of the major differences between alternative processes and silver prints where the image is suspended in a gelatin layer above a substrate.)

The first choice in making a print is selection of the type of paper.  Platinum prints can be made on most any type of pure rag papers.  A 90-pound cold press watercolor paper would be a good starting point for those that like to experiment.  I have tried a few different papers, but I continue to return to Crane’s Platinotype paper. There is something reassuring about using a paper that is manufactured for the purpose.

Processing the Print

After exposure to UV light in a printing frame, the print is ready to be processed.  I always use rubber gloves when processing prints.  The traditional formula calls for developing prints in a potassium oxalate solution and clearing them in dilute hydrochloric acid. This is pretty stern stuff in terms of toxicity and danger in handling.  Modern formulations for the developer use sodium or ammonium citrate solutions.  A replacement for the hydrochloric acid, EDTA (ethylenediamine tetraacetic acid sodium salt), can be used as a chelating agent to remove the iron from the emulsion. The modern developer is not toxic, but becomes toxic as it is used

Developing-out of the image is immediate.  Rinsing the excess developer from the paper takes a minute or two, and multiple successive clearing baths take about five minutes each. Washing time is comparable to any archival silver print.  In terms of longevity, prepare to purchase and mix new developer about every five years or so.  It doesn’t really wear out. I had my first batch of developer about seven years. Clearing baths exhaust quickly, so they must be replaced very frequently. A very light touch on the back of the print with a soft rubber squeegee can help speed drying.

     

References

Background and biographical information is from Wikipedia articles on:

Wikipedia: Platinum Prints…
http://en.wikipedia.org/wiki/Platinum_prints

Wikipedia: John Herschel…
http://en.wikipedia.org/wiki/Sir_John_Herschel

Web Sites and Blogs:

Unblinking Eye: A Guide to Platinum Printing…
http://unblinkingeye.com/Articles/QAlt/qalt.html

Alternative Photography: The platino-palladiotype process
http://www.alternativephotography.com/process_platino.html

Brainy Quote: Photography Quotes
http://www.brainyquote.com/quotes/keywords/photographs_5.html