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Moersch Tanol Speed: more on pyro developers (June 16, 2009)

Developers based on pyrogallol, the so called pyro developers or more common today PMK developers have a somewhat mythical status. On the positive side, the sharpness, latitude, dynamic range are noted. On the negative side there are aspects like toxic chemicals and the unpredictability of the staining process. The basic idea behind these staining developers is the fact that with an increase in silver density the pyrogallol builds up a layer of dye with a color that can be greenish but also red-brown. This dye will fill the holes between the silver molecules and will smooth the grain impression. This is a valuable property for very high density areas in a negative where over exposure will produce grain clumping. Edge effects improve the sharpness impression and the highlight separation will produce prints with a finely differentiated tonality, reminiscent of the fine art prints with large negative sizes.
Staining developers are often placed in the context of medium and large format photography. But the 35mm negatives can be developed in pyro too. The only problem is the control of contrast. The advantages of pyro shine in situations with a high contrast. Due to the staining action lower contrast negatives look quite dull and need a very high contrast filtration to get a decent print. With an automated system like the Heiland Splitgrade System printing is easier and more fun, because the period of experimentation can be reduced considerably.
The Prescysol EF formula I used in a previous test gave excellent results, but the shadow densities were a bit a the low side . Moersch Chemie in Germany has a different formula based on pyrocatechol and claims also a different colour of the stain. For this test I used Tanol Speed and Tmax 100.

Effective film speed

The Tmax100 film did kill the famous Kodak Panatomic X that was rated at ISO32. Kodak claimed that the Tmax100 offered the same fine grain and sharpness with a higher speed of ISO100. In most developers the true speed of the Tmax is closer to 64 than to 100 and for really good shadow detail it is often best to set the exposure meter to EI = 50. In most situations this level of shadow detail is not present and a full stop under exposure is no problem. For this test I used EI = 64 on the Gossen Mastersix meter. This speed can be fully exploited with the Tanol Speed developer.

Characteristic curve.

The density measurements of stained negatives with a normal colorblind densitometer are a bit unreliable because of the color of the stain, but as a starting point they are quite useful. below the graph of the Tanol Speed shows a truly excellent curve, very close to what the Zone System demands. The base + fog is D=0.20 and the Zone I with a D=0.11 is very good, much better than what you get with the PrescysolEF developer.


Note that the Tanol/Tmax combo delivers a useful dynamic range of nine stops, much more than the current state of the art of the high end digital sensors in top class cameras.


The grain is quite small, but not invisible. The smoothing effect is there, but only in the highlights, in the shadows and mid tones there is some grain to be seen at bigger enlargements (+10 times).


The resolution is quite high with a resolution value of 80 lp/mm that can be easily detected and a maximum resolution of 90 lp/mm that will be buried in grain clumps and light scattering in the negative.


The Heiland TAS was used to develop the films and produce consistent results. The development time with 15 minutes is quite long, but the TAS does the work for you. I worked with the recommended temperature (20 degrees C) and movement (twice per minute).


The Moersch Tanol Speed staining developer is a most intriguing product that can enhance the quality of the prints significantly. It is not a general purpose developer like the Schain HRX range or the CG512 or the FX series designed by Geoffrey Crawley. The developer and print need a longer period of accommodation to get the best results and the combo is best used when the scene brightness range is high, at least six to seven stops from deep shadow to highlight. Some experience with an exposure meter is required. In the recent past this requirement would be obvious, but today most persons rely blindly on the auto-exposure options in the camera.
I am inclined to state that the Tanol developer is the best pyro solution I have seen. With some care the prints are really convincing and a proof that inkjet printing is not the only option to create fine art images. The reproduction of specular highlights is much better than what you can achieve with inkjet technology.
Film and chemicals are free moving products. If you find a sensor that satisfies your requirements, you have to accept the camera and its system. With film, you can load any camera with the product and get identical results. You can switch from M3 to M7 or MP and do not loose anything in the process.
The main problem with digital prints is the exaggerated edge contrast and the burned out high lights. The main problem with chemical prints is the more extended workflow. But if you have ever felt frustrated by the inkjet printer that refuses to print on your favorite paper, you will appreciate the ease of sliding a paper into a bath of chemicals. It is safe to state that the M7 is an end-of-line product and so is the Tmax film or the Delta100 film. No developments or progress can be expected here. We may even cross our fingers, hoping that the products may be available in a five year time span. As long as small entrepreneurial companies like Moersch or Schain can create products that exploit the characteristics of film technique to the most, the case for classical photography is not lost. And as a bonus you do not need to buy Photoshop or a pile of books about this product. How many films can you buy if you do not buy Photoshop?

Film is not dead and a potent competitor to digital imaging. It would be nice if the mainstream writers on photography would allow themselves not to jump on any bandwagon that passes along. I got a number of messages by readers who question the quest for high levels of resolution, claiming that it is not possible to show high definition in practical work.
The next part will address this most interesting topic.