[pure-silver] Re: D76 1:2 and 1:3 - Bob Y
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sat, 27 Aug 2011 18:55:07 -0700
----- Original Message -----
From: "Bob Younger" <ryounger@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Saturday, August 27, 2011 5:57 PM
Subject: [pure-silver] Re: D76 1:2 and 1:3 - Bob Y
Janet, good question, sorry I didn't explain more. A
complete agitation for
me would be two agitations each direction (front/back and
left/right) if in
trays; and four inversions with rotation if I'm using a
canister. Either
way, an agitation takes 10-12 seconds. And to explain a
little further, just
to avoid any potential uneveness when developing in trays
since I always
lift from the front, I will turn the print around in the
developer 2-3 times
during development.
Bob
Agitation varies with the type of film and technique.
For small tanks (roll film) Kodak usually specified
inverting about once a second for five seconds repeated
every 30 seconds. Ilford recommends agitating for ten
seconds onece a minute. This as some effect on time but is
similar because the amount of agitation is similar. I find
that the longer interval for longer time seems to give me
less effect from surges, etc. Both also show "continuous"
agitation times, usually meaning the film is to be see-sawed
in a tray. There are also drum times shown for some film and
developer combinations. Usually drums provide the most
continuous agitation and the least development time for a
given contrast index.
For sheet film the charts usually show tray, large tank
times, and often also drum times.
The usual large tank agitation is to remove the stack of
film holders from the tank and allow it to drain for a few
seconds, replace it and remove it again allowing to drain in
the opposite direction. The agiation is repeated once a
minute. Some researchers, notably Dr. Richard Henry state
tha this is the least uniform of all methods of development
but it has been a standard for sheet film for many decades.
Tray or continuous agitation is applied to either single
sheet agitated continuously like paper prints or to a group
of films shuffled in the developer. I suspect that the
shuffline technique results in less exposure of the surfaces
of the film to the developer and possibly results in less
uniform and slightly slower development than for single
sheets.
Drum development again has continuous motion of the
developer over the film surface so has rapid development.
The uniformity while it should be theoretically ideal is, in
my experience, not so because of the lack of turbulance in
most drums. The used developer is run back and forth over
the same areas of film which can result in streaking. I
agitate sideways occasionally when using print drums on
electric rollers for film.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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