FX-55 tonality

FX-55 is Geoffrey Crawley's new ascorbate developer.
I mention it because it appears to give a rather special tonality.
Mine was made up in propylene glycol using excess potassium carbonate,as suggested by Patrick Gainer:
www.apug.org/forums/forum37/53995-new-fx-55-developer.html
If preferred the part B can be made up just before use as Crawley suggested.
I develop for double (2x) the Xtol 1+1 times at www.digitaltruth.com/devchart.html
My agitation is 30s start then 2 inversions on each minute.This is about 50% longer than Crawley's times,he agitates every 15 sec.
On the attachment I have plotted the curves for Delta 100 in FX-55 (from Crawley's AP article) and in ID-11 (similar to D-76, from Ilford's data).
The curves suggest a higher contrast for FX-55 in the lower mid tones.
I made prints from negatives of the same scene in different developers.FX-55 gave somewhat higher mid-tone contrast than Xtol 1+3, more than PC-TEA and a lot more than D-76 1+1.As its pH is only about 8 FX-55 gives fine grain although with low sulfite it is an acutance developer not a solvent developer.
Anyhow this first rather unscientific tests suggests FX-55 has potential for interesting tonality.

Alan,
how did you make the working solution:
1) adding 10 ml of B glycol solution to 1 liter made of 100 ml A solution and 900 ml water
or
2) adding 10 ml of B glycol solution to 300 ml made of 30 ml A solution and 270 ml water ?

From your curves, the contrast looks about the same. But there are some other things that bother me. Your curves show a extraordinary speed increase. Has the FX-55 curve been shifted to the left? I also notice the pronounced shoulder in the FX-55 curve, contrasted to the "straight line to infinity" for the ID-11 curve. That would suggest that films developed in FX-55 suffer severe highlight compression and are intolerant of overexposure. Could you expand on your experiences?

Hi Igor,
Here is the formula I calculated and used,it is essentially the same as that given by Pat Gainer except I believe he rounded it off.
FX-55 in Propylene Glycol (adapted from Amateur Photographer 13 Sept 2008)
Part A
Potassium Carbonate anh 24.53g
Sodium Bicarbonate..........1.5g
Sodium Sulfite.................25g
Sodium Metabisulfite.........12g
Distilled water to.............1000ml
Part B
Ascorbic acid (vitamin C)...11.56g
Phenidone.........................1g
Propylene glycol.................80ml
Dissolves on heating to 160F and stirring,unavoidable hazard:flammable and can cause burns,wear protective gear, see threads on safety making PC-TEA.
Finally make up to 100ml with propylene glycol.
For use take 100ml Part A + 10ml Part B to make 1000ml working solution,pH~8
Develop for double(2x) the Xtol 1+1 times at www.digitaltruth.com/devchart.html
Agitate 30s then 2 inversions on each minute.

Norman,
I think you are probably right about one of the curves being shifted,I just took them off the data mentioned to show the difference in tonality which I confirmed with a few prints in different developers.
IIRC, Crawley has written that he believes sodium is more active than potassium in a developer.If the less active Potassium is used there is an increase in shadow detail and speed as the film gets longer in the developer before the mid-tones are correctly developed.
I have not yet done proper testing of film speed or photography of white clouds in blue sky so cannot answer the highlight question.Might be lucky,maybe it will make usually straight line tabular grain film like S-shape traditional film,not tested yet.

Many thanks, Alan.

More tests.
I did not find much difference between FX-55 in Glycol and PC-TEA 1:50 using T-max 100 film and 8x enlargements.
The FX-55 takes 50% longer to develop.
There is no difference in average metering EI, both had EI=80 sun/shade.
No perceptible difference in grain or acutance on 8x enlargement.
Tonality can be equalized by using higher contrast with PC-TEA.
Perhaps there are subtle differences only apparent on larger prints.