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Photo Forum / Film Photography / Darkroom / April 2006Prewarming film emulsion
Recently, while inquiring about E-6 kits at my local camera store, one of the co-owners (brothers) described one of the kits, Tetenal, I think. Reading from a product description, he said that particular kit required one to "prewarm" the emulsion, presumably using warm water at 104 degress Fahrenheit. This got me to thinking: Could one use a similar approach with B&W? While I'm not sure how it would affect development times, softening the emulsion may enable the developer to do its work. (However, I should note that it's been some time since I developed ANY film.) Dieter Zakas  SignatureGood, better, best; never let it rest, until your good is better and your better is best. (Billy Cox) > Recently, while inquiring about E-6 kits at my local camera store, one of > the co-owners (brothers) described one of the kits, Tetenal, I think. [quoted text clipped - 6 lines] > emulsion may enable the developer to do its work. (However, I should > note that it's been some time since I developed ANY film.) Most if not all manufacturers recommend that you do not "prewet" the films prior to development as the water in the emulsion may impede develoment progress and uneven development is theoretically possible. Note that I've never heard of such a case. The other reason that don't recommend the practice is that the rinse tends to rinse out the wetting agent that is included in the film. SignatureRegards, John S. Douglas, Photographer & Webmaster http://www.puresilver.org - http://www.legacy-photo.com John spake thus: >> Recently, while inquiring about E-6 kits at my local camera store, one of >> the co-owners (brothers) described one of the kits, Tetenal, I think. [quoted text clipped - 13 lines] > recommend the practice is that the rinse tends to rinse out the wetting > agent that is included in the film. So what difference would that make? Once the film is wet, why would you need wetting agent? Signature... asked to comment on Michigan governor George Romney's remark that the army had "brainwashed" him in Vietnam—-a remark which knocked Romney out of the running for the Republican nomination—-McCarthy quipped, "I think in that case a light rinse would have been sufficient." (Eugene McCarthy, onetime candidate for POTUS) > So what difference would that make? Once the > film is wet, why would you need wetting agent? The instructions could read; " Pre-wet or not as you damn well please." That being the case anyhow. Perhaps it's a left-over selling point which used to read, "no pre-wetting required". There are some left overs and some that should have been left over. Dan dan.c.quinn@att.net spake thus: >> So what difference would that make? Once the film is wet, why would >> you need wetting agent? [quoted text clipped - 5 lines] > There are some left overs and some that should > have been left over. Dan Well, it does no harm, so I do it. Worst effect is possibly a little wasted time. Signature... asked to comment on Michigan governor George Romney's remark that the army had "brainwashed" him in Vietnam—-a remark which knocked Romney out of the running for the Republican nomination—-McCarthy quipped, "I think in that case a light rinse would have been sufficient." (Eugene McCarthy, onetime candidate for POTUS) > dan.c.quinn@att.net spake thus: > [quoted text clipped - 10 lines] > Well, it does no harm, so I do it. Worst effect is possibly a little > wasted time. Prewetting causes developer dilution, especially if you are processing with critical quantity of developer. Kodak C-41 process does not suggest prewetting. > The other reason that don't recommend the > practice is that the rinse tends to rinse out the wetting agent that is > included in the film. If that's the case how would the other three solutions fail to wash out the wetting agent/ or do you mean there is wetting agent incorporated to make the initial developer evenly coat the film? Btw I have never added wetting agent to any film prior to the final rinse. Signature"To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 www.gregblankphoto(dot)com >> The other reason that don't recommend the >> practice is that the rinse tends to rinse out the wetting agent that is >> included in the film. > If that's the case how would the other three solutions fail to wash out > the wetting agent/ or do you mean there is wetting agent incorporated > to make the initial developer evenly coat the film? I believe that it is included in the emulsion during the coating. SignatureRegards, John S. Douglas, Photographer & Webmaster http://www.puresilver.org - http://www.legacy-photo.com >Most if not all manufacturers recommend that you do not "prewet" the films >prior to development as the water in the emulsion may impede develoment >progress and uneven development is theoretically possible. Note that I've >never heard of such a case. The other reason that don't recommend the >practice is that the rinse tends to rinse out the wetting agent that is >included in the film. November 26, 2005, from Lloyd Erlick, And here I've been pre-soaking my film before the developer for lo these many years ... oh, well, wrong again. regards, --le Signature________________________________ Lloyd Erlick Portraits, Toronto. voice: 416-686-0326 email: portrait@heylloyd.com net: www.heylloyd.com ________________________________ Lloyd Erlick spake thus: >> Most if not all manufacturers recommend that you do not "prewet" >> the films prior to development as the water in the emulsion may [quoted text clipped - 5 lines] > And here I've been pre-soaking my film before the developer for lo > these many years ... oh, well, wrong again. I wouldn't say "wrong"; it's hard to see how a presoak could have any ill effects, like uneven development. Seems to me it would have quite the opposite effect, as the emulsion is thoroughly wet and the chemistry can more easily diffuse through it. Wonder what Richard K. has to say about this. Signature... asked to comment on Michigan governor George Romney's remark that the army had "brainwashed" him in Vietnam—-a remark which knocked Romney out of the running for the Republican nomination—-McCarthy quipped, "I think in that case a light rinse would have been sufficient." (Eugene McCarthy, onetime candidate for POTUS) > And here I've been pre-soaking my film before > the developer for lo these many years ... oh, > well, wrong again. Practice, practice, practice ! Like I said, I've never heard of it being a problem. I asked Kodak about it and was told that it's just an unnecessary step for the most part. I'll save 2~3 minutes where I can these days. SignatureRegards, John S. Douglas, Photographer & Webmaster http://www.puresilver.org - http://www.legacy-photo.com Phototherm's black and white programs prewet the film and Jobo has in the past (and may still) recommend a five minute prewash when processing black and white. Since the temperature that black and white is normally processed at is only a little above room temp the pre-wet is not so much for tempering as it is for evenness of development. I currently use a Unicolor Film Drum and motor base and use a five minute prewash. I have tried shorter presoaks and with some combinations of film and developer got less than ideal results. If you are going to use a presoak with black and white stick with 5 minutes. (At least until you can test and come up with a shorter standard minimum time that works with all the combinations and permutations of film type, developer type, temperature and agitation that you will use in your own work!) Signaturedarkroommike ---------- > Recently, while inquiring about E-6 kits at my local camera store, one of > the co-owners (brothers) described one of the kits, Tetenal, I think. [quoted text clipped - 8 lines] > > Dieter Zakas Dieter Zakas a écrit : > Recently, while inquiring about E-6 kits at my local camera store, one of > the co-owners (brothers) described one of the kits, Tetenal, I think. [quoted text clipped - 8 lines] > > Dieter Zakas E-6 pre-warming is usually done *without* water, often during 5' to warm up the tank/reel/film before 1st developer in which temperature is critical. For B/W, both schools exist: pre-wetting or not. Pre-wetting can be useful for short development times and reduces the risk of developer streaks with larger formats. You have to adapt your development time. Personally I don't feel the need to pre-wet ... Best regards, Claudio Bonavolta http://www.bonavolta.ch > Dieter Zakas a écrit : >> Recently, while inquiring about E-6 kits at my local camera store, one of [quoted text clipped - 12 lines] > E-6 pre-warming is usually done *without* water, often during 5' to warm > up the tank/reel/film before 1st developer in which temperature is critical. Thank you, Claudio, for setting me straight. I'd forgotten that the prewarming was for the tank and reel, as I recall. Where I got the notion that one would warm up the film emulsion is beyond me. Even so, it probably couldn't hurt: after all, which would you rather do: spread butter taken from the freezer on your toast, or use the butter that's been on the breakfast table for ten minutes? Dieter Zakas Emulsion, NJ SignatureGood, better, best; never let it rest, until your good is better and your better is best. (Billy Cox) > Recently, while inquiring about E-6 kits at my local camera store, one of > the co-owners (brothers) described one of the kits, Tetenal, I think. > Reading from a product description, he said that particular kit required one > to "prewarm" the emulsion, presumably using warm water at 104 degress > Fahrenheit. Well unless it states prewarming is done with water as a prewet, it is an assumption. Not always good to assume! > This got me to thinking: Could one use a similar approach with B&W? While > I'm not sure how it would affect development times, softening the emulsion > may enable the developer to do its work. (However, I should note that it's > been some time since I developed ANY film.) Here's my take: you'll get as many answers as practitioners, but prewetting 5 minutes seems excessive, however 5 minutes prewarming is probably correct, you do want to have the film-reel and tank at the process temperature. By prewarming your insuring the times are accurate for development, because times are established (hopefully) without lag time factored as an unknown. Any time the film etc must come up to the process temp -lag time exists. I typically do prewash my large format film, ONE/TWO minutes only....I feel it washes out the back anti reflection coating and does warm the film up more quickly....I have never had problems but I bidirectionally rotate or rock my drum drums during process. I am quite sure there are many correct answers to your question as the process can take a lot of variation and still yield VG results. Signature"To announce that there must be no criticism of the President, or that we are to stand by the President, right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public."--Theodore Roosevelt, May 7, 1918 www.gregblankphoto(dot)com : > Recently, while inquiring about E-6 kits at my local camera store, one of : > the co-owners (brothers) described one of the kits, Tetenal, I think. : > Reading from a product description, he said that particular kit required one : > to "prewarm" the emulsion, presumably using warm water at 104 degress : > Fahrenheit. : Well unless it states prewarming is done with water as a prewet, it is : an assumption. Not always good to assume! I've used the Tetenal kits with my Jobo and the prewarming was done with the film in a "dry" tank. There's no prewash or prewet. : > This got me to thinking: Could one use a similar approach with B&W? While : > I'm not sure how it would affect development times, softening the emulsion : > may enable the developer to do its work. (However, I should note that it's : > been some time since I developed ANY film.) : Here's my take: you'll get as many answers as practitioners, but : prewetting 5 minutes seems excessive, however 5 minutes prewarming is [quoted text clipped - 3 lines] : time factored as an unknown. Any time the film etc must come up to the : process temp -lag time exists. : I typically do prewash my large format film, ONE/TWO minutes : only....I feel it washes out the back anti reflection coating and does : warm the film up more quickly....I have never had problems but I : bidirectionally rotate or rock my drum drums during process. : I am quite sure there are many correct answers to your question as : the process can take a lot of variation and still yield VG results. As you know I use a five minute prewash. I started doing so when I first got my Jobo and that's what they recommended. Like you I've gotten good results with a five minute prewash and I don't see any reason to change. :-) Of course all I do is turn on the motor, pour in the water as I start a timer and then I can walk away for the five minutes. :-) For what it's worth I would agree that after two minutes the emulsion has more then likely absorbed as much water as it's going to and extending the prewash to five minutes isn't providing any added benifit. Signature------------------- Keep working millions on welfare depend on you There is no need to 'pre-warm' B&W film, as development occurs at room temperature. E-6 films run at 100F. > Recently, while inquiring about E-6 kits at my local camera store, one of > the co-owners (brothers) described one of the kits, Tetenal, I think. [quoted text clipped - 11 lines] > Good, better, best; never let it rest, until your good is better and your > better is best. (Billy Cox) In the case of conventional (i.e. not chromogenic C-41-type) black-and-white film, there is no reason to perform pre-warming provided the film is around room temperature to start. Some people *do*, however, advocate pre-*wetting* film especially to avoid uneven development due to 'dry' patches as the developer is poured into the tank - even more especially with shorter developing times. I prefer not to mess around with too short a developing time in any case, and I find no advantage at all in pre-wetting black-and-white film, proper immediate agitation gets rid of any dry spots as the developer is poured in. In the case of C-41 chromogenic or colour negative film, development temperature is 38 degrees Celcius. In this process I always perform 1 minute of pre-wetting at that temperature - for two reasons. Firstly, it assures the film is up-to-temperature and wetted prior to development, which takes 3mins 15seconds - 3mins 45seconds depending upon how many rolls have been through. Secondly, it clears away the green anti-halation layer which otherwise builds up rapidly in the developer solution. On the rare occasion that I have processed E-6, I have done the same. My regards, F.C. Trevor Gale. > There is no need to 'pre-warm' B&W film, as development occurs at room > temperature. E-6 films run at 100F. [quoted text clipped - 14 lines] >>Good, better, best; never let it rest, until your good is better and your >>better is best. (Billy Cox) |
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