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Prewarming film emulsion



 
 
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  #11  
Old November 27th 05, 03:27 PM posted to rec.photo.darkroom
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Default Prewarming film emulsion

In article , Claudio Bonavolta at
wrote on 11/26/05 5:30:

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.
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


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
--
Good, better, best; never let it rest, until your good is better and your
better is best. (Billy Cox)

  #12  
Old November 27th 05, 07:11 PM posted to rec.photo.darkroom
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Default Prewarming film emulsion

On Sat, 26 Nov 2005 09:25:06 -0600, Lloyd Erlick Lloyd at dot com
@the-wire. wrote:

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.

--

Regards,

John S. Douglas, Photographer & Webmaster
http://www.puresilver.org - http://www.legacy-photo.com
  #13  
Old November 27th 05, 11:13 PM posted to rec.photo.darkroom
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Default Prewarming film emulsion

David Nebenzahl wrote:

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

  #16  
Old December 1st 05, 10:14 AM posted to rec.photo.darkroom
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Default Prewarming film emulsion

Gregory Blank wrote:
: In article ,
: Dieter Zakas wrote:

: 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
: 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.

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.
--




-------------------
Keep working millions on welfare depend on you
  #17  
Old December 1st 05, 02:41 PM posted to rec.photo.darkroom
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Default Prewarming film emulsion

There is no need to 'pre-warm' B&W film, as development occurs at room
temperature. E-6 films run at 100F.


Dieter Zakas wrote:
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
--
Good, better, best; never let it rest, until your good is better and your
better is best. (Billy Cox)


  #18  
Old April 1st 06, 03:36 PM posted to rec.photo.darkroom
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Default Prewarming film emulsion

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.

UC wrote:
There is no need to 'pre-warm' B&W film, as development occurs at room
temperature. E-6 films run at 100F.


Dieter Zakas wrote:

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
--
Good, better, best; never let it rest, until your good is better and your
better is best. (Billy Cox)




 




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