Donald, cooper path it's known to work with CMS 20.
I wouldn't expect C-41 bleach to work, unless via forming silver chloride and then using an ammonia bath to remove only the chloride.
What I'd be tempted to try with CMS-20 or other document films is apply a halide-reactive toner (like the sepia/sulfide toner that was used in Kodak's T-Max Reversal Kit) to allow developing the positive image before bleaching. Then you can use a C-41 blix to remove the silver developed in the first dev. This probably wouldn't work with conventional films; you'd have too much fog in the highlights where silver that didn't develop took the toner, but CMS-20 shouldn't have much of that problem due to the monodispersed thin emulsion (if I've understood correctly why that makes the film high contrast by nature).
Only in the most generic terms could you regard a paper developer as a suitable reversal first developer & even then it's something closer to the 'universal' type of developer that you want. What's more important is how it is engineered to perform in the specific situation.
David Wood (aganist silver solvent tradition) has been recommending bare (high contrast) Kodak D-11 for the first developer, a bit conceptually in the way of the Scala process you pointed, being paper D-72 (Dektol) a good choice for the second round. I agree with this: Energy instead silver solvent
Of course, but it's surprising that a manufacturer of the ilford's size says that about his film, instead showing a suitable recipe
I'll second that. HP5 works well, just leave out the solvent. I consider it a film that works well naturally.
BTW @Ian Grant has published several reversal formulas on his website: http://www.lostlabours.co.uk/photography/formulae/formulae.htm. All of them appear to be high energy developers.
Isn't this a false dichotomy? First developers have always been high energy (paper strength) developers but some of them have appropriate amount of silver solvent. Is there a first developer in the literature that is low energy and uses silver solvent? How would such a developer build the contrast needed for slides?
David Wood (aganist silver solvent tradition) has been recommending bare (high contrast) Kodak D-11 for the first developer, a bit conceptually in the way of the Scala process you pointed, being paper D-72 (Dektol) a good choice for the second round. I agree with this: Energy instead silver solvent
He also says: "The SCALA process uses a LIGHT-reversal procedure. We feel this is the wrong approach to reversing B&W film." In don't agree with that, here I'd say YMMV.
, Ron found some aspects of the dr5 process rather oddly backward, ut it's what works that counts.
Light reversal
Hi teacherIt's a few years now since I did some work for a lab in London (UK) planning to introduce a B&W Reversal service, unfortunatel it's still commercial and as they paid for it legally and morally I can't publish the final formula at the moment. When I get time I'll revisit my notes, this lock-down means I have gardening and housework priorities to keep the other half happy
Around that time dr5 moved location abd Dave Wood had issues, due to a change in water supply, he turned to Ron Mowrey (PE) for help and I rember Ron and I discussing it in a telephone call, Ron found some aspects of the dr5 process rather oddly backward, ut it's what works that counts.
Ian
Meanwhile, clean highlights are much more important and that's what makes clear base films so nice to project. Rollei Retro 80S looks spectacular when reversal processed.
Well... with a controlled light reversal we are able to not fog all the halide the bleaching left. We have that "unused silver"...
If we don't fog that silver then second development won't develop it in the highlights, but we may develop it in the shadows via infection... extending dynamic range for the the projection, this is my guess...
+1Except that D-11 has much higher sulphite levels & it has a drastically different ratio of M:Q compared to the disclosed Agfa first developer. D-11 will almost definitely be foggier than the Agfa first developer. The Agfa developer is considerably more sophisticated - the PEG likely slightly swells the gelatin as well as accelerating the development, enabling much better penetration of the developer components into the totality of the emulsion(s), which then develop at a more simultaneous rate (likely from knowledge from colour processing research- which seems to have been the background of at least one of the Agfa patent holders). A more polydisperse, less tightly packed emulsion with less complex layer structures may well develop enough of the silver without needing accelerators or solvents (though who knows, maybe HP5+ has polymeric extenders in the emulsion which have effects in line with adding PEG to the developer).
Mr Wood sometimes lets his opinions get in the way of the very high quality imaging science work done by Agfa, Kodak etc on reversal processing. Light reversal is actually part of testing/ troubleshooting the reversal step in E-6. Either light or chemical reversal will work equally well, if used correctly. The other thing which immediately colours my opinion of DR5 is Wood's lack of disclaimer about the effects of grey triacetate base film on the highlights - Photo Studio 13 in their Scala process document strongly recommend that you should only use clear base film for Scala reversal processing - which is why 120 & sheet TMax 400, Delta 100/ 400 etc are recommended, but the 35mm equivalents aren't.
I guess that in BW reversal we have several control factors and YMMV. There are several ways to do the same...
But also I guess it's difficult to beat what D. Wood does after fighting a 3 decades war. It's not only the development itself but also the toning...
He says that with TXP dr5 reaches 4.70 d-max... if this is true...
There's a lot of controls we no longer use. For instance some reversal processes could vary the 2nd exposure, by varying the time or intensity of the re-exposure you can fine tune the final results. alternately the timing of the 2nd developer could be varied so development wasn't to completion. I should add these were techniques used for machine processing of B&W cine reversal films.
If we go back to E3/4 processing the 2nd (colour) development time had to be adjusted as well as te first for push processing. Most of our B&W reversal processes effectively use a full 2nd exposure and 2nd development to completion. One note is full second exposure is enough to fully fog the remaining silver halide, gross over exposure causes different issues.
Ian
some reversal processes could vary the 2nd exposure, by varying the time or intensity of the re-exposure you can fine tune the final results. alternately the timing of the 2nd developer could be varied so development wasn't to completion.
@138S Consider that a typical E6 slide has a Dmax of about 3,5 and it already is plenty high.
Ian, what is the effect produced by the two controls you described on the final result in b&w reversal?
He says that with TXP dr5 reaches 4.70 d-max... if this is true...
I think they were controls for under exposure which would result in a dense positive
If I remember correctly in Grant & Haist excellent books, on the reversal section, there's written that the human eye cannot discern densities above 2.2 or 2.4.
Good clean highlights are absolutely essential to making a transparency that looks 'right'.
Ian, were there controls which used a halide solvent in the second developer? Interestingly, PE's recommended workflow for paper reversal has a little bit of thiosulphate in the second developer, but was it also used for film?
Basic Photographic Processes and Materials, page #176:
"Although these films are capable of achieving densities over 3.0, the shadows are best reproduced at densities of 2.7 and less."
I was referring to Grant & Haist vol.2, pages 316-317:
"High maximum densities are not needed becase, as H. Verkinderen has pointed out, "by normal projection all densities-discrimination for densities exceeding from 2.2 to 2.4 is lost"
There was a short video of the Tecnolab d&d machine which Wood still uses nowadays that pictures the display of the machine. There are at least two intensification baths at the end of the process.
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