[APML]: improving Tech Pan development

[Alfredo Zanazzo <alferd@mbox.lol.it>]

Joseph O'Neil wrote:
> 
> 
> Mike Regish <mregish@village.yvv.com> writes:
> -snip-
> 
> > agitation. It says "Provide immediate agitation by shaking the tank up and
> > down 10 to 12 times for 2 seconds." Then it says "Let the tank sit for 30
> > seconds, and then start the next 20 second agitation." 10 to 12 times in 2
> > seconds sounds kind of fast. Is the "10 to 12 times" supposed to be in 20
> > seconds or is "the next 20 second agitation" supposed to be 2 seconds?
> >
> 
>     Hi Mike;
>    Try this:
>   Get your clock/stopwatch ready.  Some people choose to start their
> timer then fill the tank, others like me fill the tank then start the
> timer.  THere are good reasons for both - whatever you choose, be
> consitant and keep the procedure the same for each film.
> 
>    Once your tank is filled the first time, agitate for 5 seconds, and I
> do that by turning the tank upside down and back again once per second.
> Do not treat film like a bartendeer mixing a martini.  After your 5
> seconds agitation, give it a soft "thump" to dislodge any air bubbles on
> emulsion.
> 
>   Repeat this procedure - either once every 30seconds/5 agitations or 60
> seconds/10 agaitations.  I always give a soft thump after every agitation
> becase I find air inthe tank can re-attach to film emulsion during
> development.  not common, but it happens once in an odd while.
> 
>   Remeber - whatever you do - be consistant.  You'll do fine.
>   Joe

Joe,
If I may add a suggestion, it is pour water int the tank at more or less
the same work temperature of developer, leave the film emulsion get wet
for a  few minutes, than empty the tank and put the developer, starting
process.
In this way developer is going to reach emulsion surface a little slower 
and more gently, avoiding any kind of possible spots.
I add to developing time   10 seconds to compensate the slower action.
I fill the tank without cover and reel with water and than in the dark
I put the reel with the film into and close.
About agitation: after have seen how professional lab get contrast and 
saturation by developing with electric pumps moving chemicals 
continuously and regulary I thought to try something similar with TP.
I have built a simple device with a plastic pot and a 12V
motor with 1 round X 3-4 seconds (better if you can invert direction
evry minute).
The motor is fixed to a wooden base and its shaft to the center of the
bottom of the pot.(Just a little bigger than your tank)
I put the tank into it and switch on the motor
The base of the wood is  a little inclined to let the liquid move 
continuosly on the surface of film and a piece of plastic fixed to the 
base is forcing a
little against the coarse  external pot surface so that it creates a 
vibration
almost identical to an electric professional developing pump.
I have compared results obtained in the old fashioned way and with this
simple  and unexpensive device (it took 2 hours time to build it) and it 
makes a difference!
Contrast has increased and results are constant.
As I use 4X5 it is very easy to get spots on the film, but not with this
method.
In case someone is interested i could explain it better, but just to 
have an idea...
It is less work and worry too! A motor is for sure more precise and
constant that your hands!
I think Wallis has also adviced to soak film before developing in his
book.
Ciao

-- 

--
Regards, Alfredo Zanazzo ( alferd@mbox.lol.it )


Concentric Schmidt Cassegrain photos: 
http://www.lol.it/~alferd/astropag.htm