Second exposure of 120 roll film

Hans Borjes · Mar 14, 2006

According to my first 3 trials, the second exposure of 120 roll film in reversal processing seems to be tricky. I would expect it to be easy with sheet film. 135 size film might be easier as well, but with medium format film I have experienced uneven density of the black space between the images, not to speak about the images themselves.

I wonder whether it is possible at all to achieve the same homogenous fogging exposure with this film size as with chemical fogging?

David A. Goldfarb · Mar 14, 2006

What kinds of reels are you using? As much as I prefer stainless, I would use Paterson white plastic reels or maybe someone makes a clear plastic reel (Jobo?) that would permit an even fogging exposure, or maybe even use one of the tanks with film aprons and unroll it for the fogging exposure. Or even another option might be to unroll the film for the fogging exposure and do the remaining steps by the "seesaw" method, rather than on the reel.

Hans Borjes · Mar 14, 2006

David A. Goldfarb said:
What kinds of reels are you using?

I am using the reel
http://jobo.com/jobolab/produkte/images/150201.jpg

in the tank
http://jobo.com/jobolab/produkte/images/1520.jpg

To remove a softened FP4 from the reel is not feasible without destroying the emulsion.

Has anyone practical experience?

Gerald Koch · Mar 15, 2006

It is easier to switch to SS reels and tank rather than to fuss with a chemical fogging agent. You also need a strong source of light, a 250 watt bulb at 2.5 ft is what is usually recommended.

htmlguru4242 · Mar 15, 2006

I've done this with my regular plastic (ick for 120) reels (It's an AP tank).

The first time that I did reversal, it was with 120 film. I held the open tank under a bright light for about a minute or so and then took the reel out, rotating it in my hand so all sides got light. I got good results the first time (which was my first time ever reversal processing as well).

The edges of the film (just black space) are uneven, but that's no big deal. The rest of them are pretty even. i think that you just need a long enough exposure.

Hans Borjes · Mar 17, 2006

Now, by own experience, you are right: it just needs enough light. I am actually quite surprised that all the reversal recipes are so fuzzy regarding the amount of light.

I have not proven that with 120 roll film, but yesterday we have been light-reversing a Fomapan R100 using a simple IKEA "Tertial" office lustre with a reflector. We fitted it with a 100W bulb for the short period of second exposure (although we know that 100W would kill this lustre in normal operation). We adjusted the distance between the reflector and the table so that the Gossen exposure meter showed 10000 lux and exposed each side of the reel to the light for 3 minutes with constant rotation in a water bath. Very useful for the water bath was the transparent cover of a DVD spindle.

That gave perfectly even blacks and has not fogged the highlights.

Gerald Koch · Mar 17, 2006

Its not possible to fog the highlights as the bleached image (negative) has been converted to a light insensitive compound. If you experience any problem with veiled highlights then the amount of halide solvent such as thiocyanate in the first developer is not sufficient.

Hans Borjes · Mar 17, 2006

Gerald Koch said:
Its not possible to fog the highlights as the bleached image (negative) has been converted to a light insensitive compound. If you experience any problem with veiled highlights then the amount of halide solvent such as thiocyanate in the first developer is not sufficient.

I don't know about the reason why this can happen, maybe minimal traces of remaining silver in the highlights.

I have just seen a light-reversed TMAX - done by a lab in Berlin - that had this effect.

And I was remembering what Ilford says in its reversal recipe: "Insufficient second exposure will result in a reduction in density when the film is finally fixed. Two to four times the specified exposure may safely be given, but over exposure beyond this extent may lead to slightly foggy highlights."

Gerald Koch · Mar 17, 2006

Despite Ilford's comments, veiled highlights are almost always caused by insufficient thiocyanate or thiosulfate in the first developer and not from excess light exposure before the second developer.

Ilford's instructions for reversal processing are not the best. Their method is based on the use of easily obtained chemicals or off the shelf products. The composition of the first developer needs to be adjusted to fit the particular film being processed.

Donald Qualls · Mar 18, 2006

I recall a while back PhotoEngineer mentioned that a laundry product available in grocery stores as "Iron-Out" is a dithionite, a fogging developer for silver halides. That is, it could be used *instead of* both the reversal exposure and second developer in a B&W reversal process. That would eliminate the uneveness of exposing the film on the reel.

I don't know if this would need to be mixed with other chemicals (alkali, preservative, etc.) for actual use on film, but it might be worth some experimentation...

Second exposure of 120 roll film

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