Substitute CD-3 for CD-4?

[emo supremo]

Why do some E6 formula call for CD-4 and others CD-3. (I understand the earlier reversal processes used nastier chemicals but this 3 vs 4 puzzles me)
Can anyone explain why you can substitute CD3 for CD-4 but CD4 can NOT be substituted for CD-3
Or is it vice versa? (I think I got it right)
Also, if you have tried, did you swap mole for mole or is the molecular weight close enough to swap gram for gram?
Also, it seems to be the most labile. Has anyone tried fortifying the formula by a extra percentage CD4 to bring the strength back up?

[Dave Grenet]

Real E6 uses CD-3. CD-4 won't form the proper dyes and will apparently lack stability...

[emo supremo]

Thank you Dave. Is there a 'standard formula' reference for the 'real E6' is allude to above?

You see, I had purchased a set of formuli from an outfit called "ZoneV" (yes "V", i'm typing from the original in glassine sleeves) of Stratford, VT back in the late 1980's and the color developer calls for CD-4 (the chemical name and CAS number are not offered in the Zone V literature). PT carries the TWO and the FOUR. I purchased the FOUR yesterday. Shoot. Now what do I do?

I'm told CD-4 goes bad much faster than CD-3 and, therefore, substituted the THREE for the FOUR (gram for gram in Zone V formula), developed some slide film and got a dark bluish negative (not positive). Temperature control is a fraction of degree tolerance on my system. The color developer is supposedly the most labile ingredient (nothing from the lit; just verbal communication) which makes me suspect my old 1991 bottle of CD-3 is shot. Is the old bottle of 1991 stock of CD-4 worth trying?. If sources of supplies dwindle and all things being equal 3 is more stable than 4 I'd rather my time/records/results be invested in a chemical that has better shelf life.

Also, their formula uses stannous chloride which is not so stable once dissolved (6 month beyond use date). Sodium thiocyanate is supplied as a liquid so I'm casting a jaundiced eye in its direction as well.

So the question reduces to: stick with the old Zone V formula CD-4 obtained from the PT or move on to one with CD-3 supplied by <no one I know of>? Suggestions?

In the meantime, I've reordered the full complement of chemicals.

[emo supremo]

PS. My next to last sentence was hyperbole. I intended to be facetious but should alert others looking for supplies that Mike Jacobsen of Artcraft has been supplying me with CD-3. The true E6 process is feasible.