When I looked at Agfa Lupex, an old German paper, in a previous post (see
More German Paper) I complained about the contrast of the exposure. In reading about Lith printing in articles by Tom Rudman and Wolfgang Moersh I saw the opportunity to perhaps enhance the contrast.
Lith printing works by overexposing the paper then using a dilute lith developer that takes some time to develop. Rather than 'develop to completion' with a proper exposure of the paper as in conventional printing, Lith printing depends on the snatch time (time in the Lith developer) to decide final image darkness. The dilute developer helps as the development is extended to several minutes. Lith however depends on the concept of infectious development which only a few papers (if any today) possess. In this process the highlights stay relatively fixed regardless of development time but the dark areas build rapidly after some time. By judging the snatch time it is possible to play with contrast which is what I am after. One is supposed to expose for the highlights and develop for the shadows. What I don't know is if this paper is 'Lithable'.
The artistic benefit of Lith is also a range of colors depending on exposure and paper qualities. This was really not part of my goal at this point.
This is my first time with Lith so I purchased the EasyLith kit from Moersh. It is two part (A&B) and one recommended dilution is 1+20 which for me was 20ml part A 20ml part B + 800ml water.
I prepared a test image. First using conventional developer (Ilford Universal PQ) I made this print on the Lupex. This is an image I have used before and so it serves a good bench mark. The image color is cold though the paper is a 'Chamois' color as described on the label.
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| Agfa Lupex Universal PQ f5.6 80sec |
Next I made a test strip. This test strip I constructed carefully as the times involved could get very long and there are two variables (exposure and development). Since development was going to be on the order of 10 minutes I didn't want to make each strip a separate development. I decided on my exposure times based on my earlier work and decided on 60", 120", 240", and 240". These I did across an entire sheet. I then cut the exposed paper in the opposite direction to form 4 strips. However I did not cut the strips completely free. Instead I left them all attached at one end so I would have to chase four separate strips. This would allow me to develop the whole paper for say 10 minutes, then tear off a strip and place it in the stop bath while the remaining 3 strips continued to develop. I could then tear off the next strip for the next snatch time until all four were done.
The test strip turned out as follows. I have annotated it to make it easier to read. The horizontal axis is exposure in seconds and the vertical is development in minutes.
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| Test Strip for Agfa Lupex and EasyLith |
The development times were shorter than I had expected. Once the image darkened significantly the changes became quite rapid hence the variations in the times shown. Also I found it difficult to judge the development under the safelight. So selecting for the highlights I decided on the 60" exposure as the highlights are bright with some detail. I guessed that my developing would be around the 7:15 mark as 8:00 shows the highlights darkening and brings into question the Lithability of the paper (in my mind anyway).
The first exposure is here... I extended the development to 9 minutes! I kept waiting for the shadows to do dark and noticed the highlights remained bright.
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| Agfa Lupex EasyLith f4.5 60sec 9min |
Not too bad and it looked like more contrast. Confusingly it differs from the test strip in that a 60 second exposure and 8 minute development showed significant darkening of the thin light strip on that section. I tried another and developed in a little longer. I got nervous though and snatched it a 9:30 minutes.
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| Agfa Lupex EasyLith f4.5 60sec 9min 30sec |
A bit better though and the highlights stayed put. Another thing to note is the image us quite warm compared to PQ Universal.
Next I wanted to see if I could measure the contrast on my scanner. I set up these scans to turn off white balance and made the measurements unadjusted. I then looked at the histograms in Photoshop and computed the dynamic range in Log2 of each image using the formula of Log2(min/max) for each image (log base 2 is used to convert to stops). The table below summarizes the results.
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| Contrast Calculation Results |
There was an improvement of half a stop of contrast by these measurements. Of course this is a statistic from the whole image and rather dimensionless. Inspecting a couple histograms shows why the perception of higher contrast may be more marked.
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| Agfa Lupex Universal PQ f5.6 80sec |
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| Agfa Lupex Universal PQ f5.6 80sec Histogram |
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| Agfa Lupex EasyLith f4.5 60sec 9min |
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| Agfa Lupex EasyLith f4.5 60sec 9min Histogram |
The histograms yield a greater separation of the bulk of the image tines towards the black and white ends of the range which confirms the sense of higher contrast. These histograms were taken to avoid the borders so only the image intensities are represented.
Finally I had to test the idea that I was being too conservative on the exposure and dev times choices. I ran two additional prints with 120 and 240 seconds. I actually liked the the lettering on the image better at these times on the test print. Indeed I got even more contrast (.76 stops).
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| Agfa Lupex EasyLith f4.5 120sec 7min 40sec |
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| Agfa Lupex EasyLith f4.5 240sec 6min 20sec |
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