Introduction

Although there are several methods of toning that involve using dyes to color silver gelatin prints, we chose to explore the chemical-based toners. From the numerous chemical toners available (from uranium and gold solutions, to premixed, commercial toners made by such companies as Kodak) we selected three chemical-based toners for our project. There are two basic types of toning chemical methods, which Clerc explains in the following, "Toning of the silver image can be done either by replacing it by other metals (gold, platinum, etc.) or by converting the silver into a colored compound (brown silver sulfide), or into a colorless substance which can mordant suitable dyestuffs" (611). We choose to explore both practices of toning by selecting two compound-forming direct toners of iron and copper, while also choosing a bleach-redevelopment method involving sepia, which also acts by forming compounds- the sepia toning method. We requested that chemistry department staff mix solutions of chemicals for sepia, copper, and iron blue toning. These two methods of toning- direct and bleach-redevelop- produce differing results in tonal range and density. The direct toning process produces intensification of the print’s tones (i.e. enhances the density and the contrast). Intensification is defined by Neblette as follows: "Processes for increasing the density and contrast of the image are known as intensification, which is accomplished by the addition of a metal or compound increasing density or the absorption of blue and violet light" (255-256). The sepia toner, however, creates a reduction in density and contrast. We expected that the lightness of the iron and copper toners would decrease, while the sepia toner would display an increased lightness.

In addition to employing different toners, we also decided to systematically vary the filters on each print. Filters effect the contrast of the picture, with a low level filter creating a more subtle tonal scale of grays, whereas a higher filter level increases contrast, eliminating tones for a stricter black and white appearance.

Hypothesis: We hypothesized that the iron-toning and copper toning methods would produce a reduction of the lightness of the prints, whereas the sepia toning method would produce an increase in the lightness of the prints.

Further we thought that the most neutral filter (2.5) would be less intensified or devalued than the lower or more highly contrast-filtered prints (1 and 4).

Procedure

1 35 mm negative

1 enlarger

1 level 1 filter, 1 2.5 filter, 1 level 4 filter

10 x 12 trays

5 pairs of tongs

photography sink and washer

fiber-based paper

333 ml Dektol developer

1000 ml of fixer

1000 ml hypoclear

toning solutions (described below in the procedure)

colorimeter

Preparation:

We began by choosing one 35mm negative from which we produced fifteen prints. The criteria by which we determined what negative to use included tonal range and aesthetic qualities. We wanted our negative to be interesting enough to prevent it from becoming a bore over the course of our project. For the scientific purposes of our project, however, we needed a negative with a varied tonal range, which would allow us to more completely observe the effects of each toner upon the various degrees of tone in the black and white silver gelatin prints. We chose to use Ilford's multigrade fiber-based glossy paper; it was necessary to use fiber-based paper because resin-coated papers are less absorbent, and would not exhibit the tones we were seeking.

Having chosen our ideal negative and paper, we produced five prints using a level 1 filter, and setting the aperture to 8, with the enlarger raised to 8.5". We used a test strip to determine our preferred exposure time, and determined that fifteen seconds was ideal for the first filter level. Each of the twelve prints was a 'straight' print; for the sake of consistency we did not use any techniques such as dodging or burning. We used a level 2.5 filter for the next set of five prints, setting the aperture again at 8 and leaving the enlarger at the same setting. Due to the darkness of the test strip at fifteen seconds, however, we decided to expose this second series of five prints for only 8.5 seconds. For the third series of five prints, we maintained the previous enlarger setting, and increased the aperture to 5.6. We determined from the test strip that 8.5 seconds was the ideal exposure time for this last set of prints. This produced a total of fifteen prints: five produced from the level 1 filter (low contrast), five from the 2.5 filter (neutral), and five from the 4 filter (high contrast).

Our research indicated aberrances in the developing process could have significant effects upon the results of toning experiments, particularly inadequacy in types of developing solution or fixing methods. Thus we decided on a strictly consistent developing process for each print. We used a 1:2 working solution of Dektol developer and water. We immersed the prints in the developing bath for 2.5 minutes, agitating for the first minute, and then agitating five seconds per every remaining thirty seconds. Next we placed the print in a stop bath of water for thirty seconds, agitating continuously. We used a fixer known as Archival Rapid Fixer, mixed in a 1:3 ratio of fixer to water to create the working solution. We then placed the print in the fixer solution for two minutes and agitated continuously. After removing it from the fixer, we rinsed the print, agitating continuously, for thirty seconds. We followed the Permawash manufacturing instructions to dilute 32 mL of Permawash hypoclear in a 1000-mL total solution of Permawash and water to produce our hypoclear solution. To remove traces of chemicals, we placed the print in the Permawash hypoclear solution for 2 minutes, agitating constantly, then rinsed again for thirty seconds, with constant agitation. Finally we placed the print in the print washer for approximately one hour. After removing the prints from the print washer, we placed them on the drying screen, face down, to prevent dust and water droplets from contaminating our prints.

A common step in our procedures for all three toning methods was a one-minute pre-wash to dampen the print and prepare it for immersion in the toning solution. The sepia toner, a bleach and redevelop method, consisted of two solutions: we used 1 liter of Solution A, which was composed of a 20% solution of Na₂S₂O₃. Solution B (also 1 liter) was a 3M solution of HCl. We immersed the prints in Solution A, a 'bleaching' solution, for five minutes. Upon removal from Solution A, we placed the prints in Solution B for an hour and twenty minutes each. Following this immersion, we placed the print in a rinse bath for five minutes. One inconsistency in our procedure with the sepia toning was that with our first print we agitated off and on for the entire hour and twenty minutes it took the print to show the toning effects. On the second two prints we only agitated for the first twenty minutes, not realizing that it might have an effect on the results.

There are three components for the iron blue toning solution, which must not be combined until immediately before beginning the toning process. The solutions that compose the final 1200 mL toning mixture are as follows: 100 ml of ferric ammonium citrate (10% solution), 100 ml of K₃Fe(CN)₆ (10% solution), and 1 liter of a 10% solution of acetic acid. We mixed these chemicals together immediately before use, and following our standard 1 minute pre-wash, we immersed each print in the solution for three minutes. We rinsed each print for approximately one hour, although we removed one of our prints before an hour had passed, not realizing that some of the traces of yellow left by the iron-toning solution were not completely washed away. In comparison to the other two, more yellowed prints, this first print’s color seemed a clean blue and white color, but we realized later that it had not finished washing completely.

The copper toning Solution A was composed of 2.765 g of K₃Fe(CN)₆,12.075 g of sodium citrate, and 500 ml of water. Solution B consisted of 3.325 g of CuSO₄, 12.075 g of sodium citrate, and 500 ml of water. These two solutions must not be mixed until immediately before beginning the toning process, but they combine to form approximately 1 liter. We immersed the prints in the combined solution for 9 minutes, and then washed them in deionized water for 5 minutes.

We allowed each of the toned prints to dry face up on the drying screens in the photography lab. We dried each of our toned prints (sepia, iron, and copper) face up on the drying screens in the photography lab, to prevent the drying screens from leaving marks on the toned prints.

In order to determine the effects that each toning method had upon the lightness of our prints, we brought the finished prints to the chemistry lab, and began the process of taking color measurements with the colorimeter. Using the calibration tile (a "pure" white tile) we set the

white value on the colorimeter, to ensure its accuracy and consistency in detection of colors. We chose four spots from which to take measurements of color on each print- one was on the sidewalk of our image-a light gray area, another in the sky-a pale/white area, one on the wall- a darker gray area, and the last in the shadows to the side- an absolute black area. We used a small disk, designed to fit the measuring surface of the colorimeter, to find the same area on each print, and while one of us held the disk in place, the other aligned the colorimeter with the disk, allowing us to measure the same area on each print. We took two readings of each area on each print to ensure accuracy in our results. Then we averaged the readings, and plugged the data into excel, making graphs and charts that illustrate the relationship between filter level and lightness in each print.

Observations and Data

The sepia toning method was the most time-consuming and difficult method of toning. Unfortunately, the prints did not yield results as brilliant as those in copper and iron toning, which made the results of the extra effort seem a little disappointing. When we put the print in Solution A, we observed a gradual bleaching of the print (bleaching in the sense of lightness, not of chemical reactiveness). After placing the print in the B solution, there was no immediately obvious result; the toning effects occurred very slowly and were rather subtle. After approximately five minutes, we noticed that Solution B grew increasingly cloudy. A thin film formed on the images of the two prints that were not constantly agitated, indicating that perhaps the precipitate in Solution B was allowed to settle on the image in these two prints. Judging from the unexplained aberances in the sepia prints’ data- i.e. the change in luminosity for the sidewalk area of the print was enhanced on the filter 1 print, the one that was agitated continuously, whereas there was a uniform bleaching effect in all of the other data- we concluded that this precipitate film had altered the lightness of this area of the other two prints.

The final solution for the iron toning was a medium brown color, and immediately upon placing the prints in the solution, the blue-toning reaction began. The reaction went more quickly than either of the other two toning reactions, and yielded a brilliantly blue-toned print. Unfortunately, our overly hasty removal of one of the prints from the washer left an obvious yellow cast upon the blue tones of the print. Overall, we noticed that the iron-blue toning method significantly darkened or intensified the tones of the prints.

Within one minute of toning, the bleaching effects of the copper toner became apparent in the prints. The prints seemed to lighten and take on a creamy-manila color. After nine minutes, the toner produced a rich brown or reddish-brown hue, although the prints seemed noticeably lightened. An examination of the colorimeter data revealed that, indeed, there was a pattern of bleaching in the sepia-toned prints. Although there were aberrations from this bleaching trend, it is possible that we made a mistake when taking our measurements in the sky area of the prints, as that was the area we had the most difficulty in measuring. As this area was white, it was difficult to find the exact same spot each time on the different prints.

Conclusions

Our original hypothesis included the idea that the copper and sepia toners, as intensifiers, would uniformly darken the prints, whereas the sepia prints would be bleached. However, upon completing some follow-up research, we realized that we were operating from a faulty conception of the word intensification. We had thought that intensification simply meant that the tones would be darkened. The Neblette definition of intensification, however, includes the quality of increasing contrast, which might perhaps explain the why there seemed to be contradictory opinions in our research about whether copper should "intensify" or lighten the toned prints. Although the scope of our project did not include an analysis of the effects that the toners had upon the level of contrast in the prints, perhaps a suggestion for future experimentation and investigation would include such analysis of changes in contrast.

Although our misconception of the idea of 'intensification' inhibited our exploration of the effects of toners on the contrast of the prints and the effects of different levels of filter, particularly in regard to the copper prints, the sepia and iron toned prints met our expectations for being bleached and darkened. The iron-blue prints were darkened quite a lot, and the sepia prints were bleached, also an effect that we had expected.

References

Neblette, C.B. Photography: Its Materials and Processes. Princeton: D. Van Nostrand Company, Inc.,

1962

Clerc, L. P. Photography: Theory and Practice. New York: American Photographic Book Company, Inc.,

1971

Chemistry of Photography. California State Unniversity, Stanislaus. 10 March 200

<http://www.chem.csustan.edu/archive/photo/sect4.htm>.