From: F. Wentzel (fotochemiker@yahoo.de)
Date: 09/01/01-12:43:42 AM Z
Silver halide emulsions are very sensitive creations.
Someone once wrote that if you think about it, you can
easily see how sensitive photographic emulsions really
are because, after all, they are even affected by, of
all things- light!
Yes emulsions are very sensitive, but for dabbling, if
you don't want a big headache I would encourage you
not to worry. If you do choose to worry, there will be
no end to it and nevermore will you sleep well at
night. Seemingly anything and everything may have an
effect upon your emulsion and some of these effects
may be delayed in there onset. One's perfume or other
air bornes, the metals in your "stainless steel"
utensils,the copper from your pennies that jumps off
the coin and onto your finger tips... many things can
desensitize fog, slow or maim your precious emulsion.
Don't worry about it.
It will be ok!
You do not absolutely need to have the best materials
Usually, when things go wrong, it is not as drastic as
being compleatly useless......what could go wrong?
Your most likely results are a slow material of low
contrast and poor tone seperation...with too much fog.
Low speed and low contrast are not insurmountable;
more problematic is high fog, but it too can be worked
out (or around); "pepper fog" is a dead end perhaps,
but you would never get an emulsion which "didn't
work"
Well, almost never...
I did have one once which had a very good D-Max(it
developed up pitch black)without any exposure
whatsoever!
Yes and No!
It would be nice to have the the highest quality, but
something less than that may be able to work just
fine.
Amatuer emulsion work is similar to baking; you make
it and even if it comes out a bit burnt, you eat it
anyway. And next time, you try to be more careful, use
a new receipe or maybe even give up.
But don't give up.
For all pratical purposes, you probably can get by
with what ever "good quality" material you can obtain.
What you probably won't get is the same (as in
"identical") results each time, but that is not a
problem if you test each batch... even commercial
manufacturers have this problem, so what's to worry?
If you are just playing, use what ever you can get
your hands on.
If you are going to devote your life to emulsion
making, buy the best!
Fritz
--- Darryl Baird <dbaird@umflint.edu> schrieb: > I'm
working on creating home-brew silver emulsions,
> using Reed & Jones'
> SILVER GELATIN book. While looking for various
> chemical components, I
> often find listings for reagent, technical, or pure
> grades of chemistry
> available at varying levels of cost. I'm certain
> reagent (ACS?) grade is
> the best, but do I need this level of quality for
> photo emulsions, or
> would a technical or "pure" grade be ok?
>
> thanks for any input
> --
> Darryl Baird
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