Good on you! I was going to add just a little. There is some
information, not a lot, in the old literature on reversal
processing. The process really has to be tailored to the specific
material although the fundamentals are the same. Many reversal
first developers have a small amount of halide solvent in them,
sometimes thiosulfate but often thiocyanate. The idea is to
eliminate the slight fogging that causes a haze on the reversed
pictures. Also, the second developer is usually a very active
developer, like Dektol. The grain is evidently established by the
first developer so using an active reversal developer does not
result in large grain. Also, the reversal can be done using a
solution of sodium sulfide, essentially the same stuff used for
redeveloping two step sepia toner. Of course, the images are
sepia colored.
Kodak has formulas for reversal development of printing paper
in some of its old processing and chemical booklets.
Reversal processing of 8 and 16mm motion picture film was
very common but I don't remember if I ever saw published formulas
for the process.
Another note: film designed for reversal has an excess of
silver halide in it to make sure there is enough to produce full
density of the final image. Motion picture film for projection
must have rather high density and contrast to avoid looking
washed out. Probably the same for B&W slides.
I would invite reporting on any practical experience list
members have with reversal, either film or paper, and, to be
clear, on any experiments done. It is a fascinating process and,
like monobath, not widely practiced.
On 8/13/2021 12:55 PM, Laurence Cuffe (Redacted sender cuffe for
DMARC) wrote:
Dear All,
Just after I posted this query, my computer started acting oddly, so I ended up doing a full copy onto an old disk drive and a further copy of my pictures library onto another disk drive. they were old mechanical drives, so this was not a fast process, hence my delay in responding.
Many thanks to the following:
Luis Miguel Castañeda,
Terry Hosinger,
Karstwalker,
Titrisol,
and Nicholas O. Lindane for their very prompt responses to my queries about Gainers formulas and reversal processing.
It was all very useful.
Luis, Thanks for the upvote for Patrick Gainer, from what I have found on the web he seemed to be a very likeable, knowledgeable and generous man.
Terry, That was exactly the information I was looking for on reversal. The use of Sodium Bisulfate 25g/l as a substitute for sulphuric Acid, 10ccConc/l.
Karstwalker Thankyou for the same information, and the link.
Titrisol, Thanks for another upvote for Gainer, and the link:
https://web.archive.org/web/20180225015603/http://silent1.home.netcom.com/Photography/Dilutions%20and%20Times.html <https://web.archive.org/web/20180225015603/http:/silent1.home.netcom.com/Photography/Dilutions%20and%20Times.html>
to Donald Quall’s DonaldQualls collection of recipe’s some good stuff there, which will require close reading and some exploration in the darkroom.
Finally Nicholas. Over here in Ireland, Autoparts stores, do not routinely sell Sulphuric acid. My local Halfords stopped doing it in 2018, as owning Sulphuric acid in the UK now requires an explosives precursor licence. The Irish stores are subsidiaries of the UK firm. I can source it as drain cleaner, but I’m a bit leary of doing that, because I don’t know what else is in there, hence my query. I think with the help of everyone who contributed here, I’m now good to go. thanks again all,
All the best
Laurence Cuffe
On 12 Aug 2021, at 20:40, Nicholas O. Lindan <nolindan@xxxxxxxxxxxxx <mailto:nolindan@xxxxxxxxxxxxx>> wrote:
Sulfuric/battery acid should be available from the autoparts store. You can get sulfuric acid at the hardware store as acid drain cleaner but it has additives to keep if from attacking metal pipes. Or, you can order it from Photographers' Formulary or ebay. The battery acid stuff is 35% (IIRC) and less nasty than the ~90-98% 'concentrated' form.
