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From: eric@rtech.UUCP (Eric Lundblad)
Newsgroups: net.rec.photo
Subject: re: tech pan developer
Message-ID: <476@rtech.UUCP>
Date: Sat, 8-Jun-85 03:42:02 EDT
Article-I.D.: rtech.476
Posted: Sat Jun  8 03:42:02 1985
Date-Received: Mon, 10-Jun-85 21:55:14 EDT
References: <704@asgb.UUCP>
Organization: Relational Technology, Alameda CA
Lines: 41

> > Was there a note here recently about using HC-110 to develop
> > technical pan film?  If anybody has tried to do this for
> > pictorial photography I'd like to hear how it worked out.
> > 
> It may be possible to try something like water bath development which
> is normally used to produce low contrast negs.  See Ansel Adams "The
> Negative" for a description.  I suspect it would be easier and more
> predictable to just go with one of the conventional developers for
> tech pan.

	Ansel Adams used the water bath developer mostly with the older
thicker film emulsions. As I understand it, todays thin emulsions don't
hold enough developer when being put in the water bath to be usefull. I
don't believe that any film makers recommend it anymore. 

	In his book "The Negative", Ansel Adams talks about a "POTA"
developer that can be used to control the contrast of tech pan. It is
discussed on pages 251 and 254, but you should buy or find a copy to read.

	You can also experiment with HC-110 by using very dilute solutions
of 1 part stock solution to 30 to 60 parts water. Stock solution is made by
adding water to 16-ounce HC-110 concentrate to make 1/2 gallon (64 ounces).
The developing times will be very long, say on the order of 20 to 30 minutes.
You should agitate about every 2 to 3 minutes. The idea behind this is very
similiar to  the water bath developer. In this case, the dense areas of the
negative exhasts the local amount of developer very quickly since it needs so
much developer, and the solution is so weak. Therefore the dense parts spend
a fairly small amount time actually developing because agitation is
infrequent. The thin areas of the negative, however, place a very small
demand on the developer, so they spend almost the entire time developing.
The result is a much lower contrast negative than you would get otherwise.
As you can imagine, if you were to agitate, say, every 10 seconds then the
whole effect would be ruined. The big danger with this method is streaking
and uneven development of the negative. If this is a problem then your
only alternative is to agitate more often and put up with the slightly
increased contrast.

	I hope this helps.
-- 

			Eric Lundblad