Go Team Reversal ! (can I skip the fix ?)

[nick mulder]

Hi,

I have been doing some reversal processing of B+W film and was wondering if fixer was really required ...

I start with a developer which makes a negative then bleach it and clear it to leave myself with the unexposed positive of my image...

A few day ago at this stage (the re-exposure) I snapped of a section of film to see what would happen to it by just leaving it - this piece of film sat around with it latent positive image for days being exposed to light for the whole duration ...

Today I put this piece in a bowl and dropped in some developer - I could sit and watch it turn into a perfect positive before my eyes ... I then washed it thoroughly and its still good tonight....

The instructions of reversal developing that I have found been pretty specific about the re-exposure step (foot-candles per millisecond/litre per iota^squared etc...) the also specify stop bath and fixer after the re-exposure develop ...

My theory is that the image is dictated by the initial develop and that everything after the bleach&clearing bath is really just follow-through that can be done under full light - I've got the positive to prove it, it appears to have the same qualities as the rest of the film of which it was snapped that went through the rest of the process as usual

One question though:

Will the removal of the fixing wash cause any other problems with the film ? maybe it will degrade over time for some reason ?
or does fixer just neutralize leftover unexposed/undeveloped emulsion which is according to my thoughts redundant in the reversal process ?


Cheers as always for any comments -


Go team reversal!

 

[gainer]

If the second development goes to completion, there is no undeveloped silver halide left. If there were to be a problem due to lack of bleaching and clearing, it would be between the two developments, and would show in the positive image. Fixing after the second development will be necessary if the second development is not complete.

When you mix your own, the bleach is a dichromate or permanganate solution which converts the metallic silver to a compound that is soluble in a sulfite clearing solution. The unexposed, undeveloped silver halide remains and is darkened either by exposure to strong light and subsequent developing or by a fogging developer. If you want a brown toned image, the second developer can be a solution of sodium sulfide, and no second exposure will be necessary.

 

[Jordan]

What Gainer says is spot-on. I would only add that you can use an alkaline thiourea bath instead of a sodium sulfide bath -- works the same way, smells way better. I don't fix when I'm using a toning bath to replace re-exposure/re-development.

 

[Lowell Huff]

These remarks about not "needing" a fix in the reversal process are correct. For years, in the microfilm market, we a reversal kit with no fixer. There is only one real reason to have a fix bath; the methylene blue test, ARCHIVABLE, requires a measureable level of thiosulfate to satisfy the protocal.

 

[nick mulder]

I use potassium dichromate and sulphuric acid for my bleach and sodium sulphite for the clearing bath ...

The piece that I let forgo the fixer is fine and when spliced back into the rest of the film (16mm cine B+W) is indistinguishable - from now on I'm going to save my $$$ and make sure I use a good (un-exhausted) bleach and clearing bath instead...

I do have some sulphide here also, I'm going to try that today - apparently it gives an almost sepia toned +ve - I wonder what does sodium sulphide do to exposed silver ? I might try that also (with a small section)

'alkaline thiourea' - the local chem place has thiourea listed

synonym: thiocarbamide CS(NH2)2 (TOXIC) in 500g pack sizes

is this the correct thiourea ? how much would I add to make a litre solution ?


thanks for all the info (ace!)

 

[gainer]

The sulphide does not distinguish between exposed and unexposed silver. It makes silver sulphide out of it all. It's what happens to silverware when it tarnishes. Slight amounts of sulphur dioxide in the air will do it.

 

[Jordan]

Actually Pat, I think it's hydrogen sulfide in the air that tarnishes silverware, not sulfur dioxide.

Anyway, thiourea is what you want (thiocarbamide = same thing). You need to dissolve it in water, about 4 g/L, and the solution has to be made alkaline by adding sodium carbonate (I think I used 100g/L) or sodium hydroxide. Google around for thiourea or thiocarbamide toners.

 

[gainer]

Actually Pat, I think it's hydrogen sulfide in the air that tarnishes silverware, not sulfur dioxide.

.

I'm probably wrong about the fart gas too. Near Morgantown, WV, when I was a student at WVU, many autos had lace fenders (we used to call them) because every puddle of water after a rain was a sulfurous acid bath due to a nearby chemical plant. That was before 1952. Things have changed.