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> Pre-Soaking C41 ? |
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#1
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Pre-Soaking C41 ?
Do members 'Pre-soak' their C41 in warm water before putting in the C41 developer -- I did an 07/2003 dated 220 size Kodak Portra 400 VC with the pre-soak at 102oF and water came out bright GREEN with the anti-halation dye -- then I poured in some home-made stop-bath of a little Citric Acid mix, then washed out Stop quickly with water at 100oF before putting in the Bleach -- well, on scanning negatives they all scanned with a dense Blue or Blue-Cyan cast which I corrected to a large extent in PhotoShop 7 levels before uploading to Flickr. Do you know if there is any detrimental effect by Pre-soak abd stop bath as I did ?
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Computerised and Slightly DIGITISED but FILM still RULES with ME ! |
#2
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The C41 pre-soak is certainly the recommendation of an ex Kodak C41 engineer and it is what I have done in the past without your issues, Pete. However I never used a stop bath immediately afterwards. I canot think of how this would be detrimental however, it just seems unnecessary or do you mean a pre-soak then dev then stop bath. If the latter then yes I'd use a stop bath after dev and prior to bleach and in that case I cannot see that anything within your process would give the problem you describe.
Could it be connected to the age of the film which is now 12 years old, instead? Mike |
#3
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I did some detailed investigation of this about 20 years ago while researching automated process sequences for the SmartLab one-shot processor project (search for it on this site). The project was overseen by Kodak EMEA, Harrow. They were initially very doubtful about pre-soaking but rigorous testing proved the point. Temperature control is paramount and two or three ninety-second rinses in water at precisely 38°C did the trick. The dilution could be compensated for by increasing the 3min 15sec development time by 10sec (note that the tests were conducted with stainless-steel spirals, which yield slightly less less carryover).
Following Kodak's advice we went straight to bleach (no stop bath), then a separate fix. It was explained to us that this reduces the risk of leuco-cyan dye with certain third-party films (not Kodak, they added, snootily) and both bleach and fix can be re-used (but not developer). You can even recover silver from used fix. The tests involved processing Kodak C41 control strips and comparing them with a strip processed by Kodak. Their quality control dept imposed the conditions that ballast film be processed alongside the control strip. |
#4
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I have been under the impression that the colour process is all alkaline because acid kills dyes. Is citric acid alkaline? It should be called an acid if it is.
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An old dog learning new tricks |
#5
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Thanks for all you helpful replies -- I tried a weak 'Citric Acid' stop bath after the developer, then rinsed out the stop quickly before adding the 'separate' Kodak Flexicolor III Bleach then rinse 'Ilford method' then C41 Fixer. I read elsewhere there may be some 'staining' if pre-soak is used and they mentioned the leuco-cyan dye so wanted the opinions of the Venerable Experts on THIS Site !!
Argentum : as an addition : The Dev is alkaline but the Bleach is Acid PH then the Fix is alkaline or maybe 'neutral' -- I didn't want to use a stronger Stop Bath , say of Acetic Acid as I thought it would react too visciously so Citric Acid is a bit 'kinder' acid.
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Computerised and Slightly DIGITISED but FILM still RULES with ME ! Last edited by pentaxpete; 9th June 2015 at 03:33 PM. |
#6
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Definitely pre-wash for home development. Many problems are caused by splashes of water 'pre-wetting' only part of the emulsion and hence slowing down developer access to those areas causing density differences. I don't use stop..
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#7
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I have never prewashed - ever! The reasoning behind this being, any residual plain water left over on the film surface will dilute the developer, although only for a short time, this can lead to uneven developing, especialy as the developing time of 3mins 15 secs is so short.
What will aid more even development is one VERY small drop of wetting agent, just enough to break down the surface tension of the developer and aid the emulsion being soaked very evenly. I get the 'small drop' by using a syringe and release one drop from the endexit Nor have I ever used stop bath after a development stage. 3 x 30secs rinse with plain water will be more than adquate, and preserve the activity of the bleach. I also rinse the fix as well, again 3 x 30 secs before filling with the fixer. In the colour process the only time I will use a stop bath is when printing with RA4 in a deep tank. Last edited by John King; 27th December 2015 at 01:11 PM. |
#8
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I've processed thousands of rolls of c-41 in a wing lynch one shot processor and the first step is a 1 minute pre soak. I do recall the first time I ran a roll in a stainless can pouring out the recommended pre soak water and it being a purplish green and thinking "might as well finish, if it's wrecked its wrecked". It printed fine.
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#9
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Last edited by JOReynolds; 6th January 2016 at 04:06 PM. |
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