Mike -- I wish I knew! I was going to mix up some Agfa 8 film developer (water, sodium sulphite, glycin, potassium carbonate, more water), then discovered I was out of potassium carbonate. So I went looking for other glycin developers and found exactly one reference to Edwal 10 (as opposed to Edwal 12, which is well documented). I find it interesting to see the differences between the two -- Agfa 8 uses only glycin as the developing agent, while Edwal 10 uses 2. Uses borax, too. I guess I'll just have to mix some up. Hopefully if someone else has used it, he or she will chime in.
The classic Edwal developers are really Edwal 12 and Edwal Super 20. Don (DF Cardwell) has been investigating Edwal 12 and plans to reveal his findings quite soon.
These PPD developers are super fine grain with excellent tonality and sharpness (acutance), but they are now a neglected field.
It's worth noting though that Ilford produced a Phenidone Glycin developer, the proportions appear to be quite similar to Edwal 10 with the obvious swapping of the Metol for Phenidone, I have a formulae but it's un-numbered although quite possibly the basis for the original Ilfosol.
Funny you should ask. I'm preparing a short introduction to Edwal 10 and 12, and it should be 'ready for the press' (meaning APUG) in the next month.
Edmund W. Lowe (Edwal) created E-10 as a variation to D-76 back in the mid 1930s. He followed it up with a very fine grain developer with identical properties, Edwal 12. The only important difference between 10 and 12 is that 12 has a much lower pH, and produces a nearly grainless negative negative with today's advanced 400 ISO films like TMY2 and Delta 400.
While one may certainly use them diluted for one shot use,
I prefer both 10 and 12 as replenished developers.
There is a practical difference between 10 and 12: 12 uses PPD, and some folks are unwilling to work with some of photography’s potentially less friendly ingredients. Edwal 10 is just fine.
The image Edwal 10 produces, in terms of granularity, is similar to D-76, although the grain itself seems, to my eye, to be cleaner and more defined. It is a very subtle difference. It is not in any way mushy or soft. It has a neutral acutance. It is not soft, it does not produce exaggerated effects.
The tonal scale is different. Compared to D-76, the lower values are slightly darker, the midtones are the same, and the highlights are brighter. Using TMY2 as an example, E10 produces a shoulder that may be placed with precision at a density between 1.5 and 2.2, depending upon your agitation. E10, therefore, is very suitable for Minimal Agitation techniques. With agitation every minute, you can be safe to assume the curve will be very similar to D-76, with slightly deeper shadows and brighter highlights. E10 DOES give full exposure speed, the contrast rise through the shadows is lower than D-76.
In plainer terms, if I were making a picture where the shadows were more important than the highlights, I would use D-76. If the highlights were more important, I would use Edwal 10. For a balanced scene, either would do very well.
Most of my work is available light portraiture. Edwal 10 and 12 make negatives from TX and TMY2 that resemble studio work with TXP (in conditions that would be impossible to work with TXP). In short, Edwal 10 is a very carefully crafted alternative to D-76 that excels when flesh tones and highlights are important, and when local contrast in the midtones needs to be increased. It is a very good developer to use with incident readings.
For a beginner, or for all around safety, D-76 would be a better choice. Edwal 10 provides a fine second developer; a different look. On an overcast day, or in the shade, Edwal 10 !
Here is a curve from a calibrated step tablet, read through a densitometer and everything. Note that this is for a negative that was given minimal agitation, so there is a pretty dramatic shoulder, as well as more shadow density than one would expect with conventional agitation. But this suits MY work, so here is MY curve ! Hope it helps a little.
don
Last edited by df cardwell; 02-24-2009 at 02:42 PM.
Reason: typos, errors, and additions.
Lowe wrote wonderful documentation for his formulas,
including how to use variations of the basic formula,
and when to use them. Germain made an trifling adjustment in Lowe's work, and claimed it as his own.
Thank goodness we are untroubled
by such ruthless self-promotion in our era !
There is no magic bullet developer, only one that gives the best results. If the saggy curve works for you, then it is fine, but I prefer the straight line which gives me better results and is what the film was designed for.
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