Re: Dry Plate Speed & Shelflife

>> Ryuji, frankly, I am absolutely not keen on
>>competing with your semi-professional
>>(non reduction sensitized) silver halide
>>emulsion.
 
> As far as I know, this thread was about the speed
> and other characters of color blind dry plate >emulsions
from early years of silver-gelatin >process, of course for
pictorial photography >applications. It wasn't about
holography
>or about how to make emulsions.

No Ryuji, the original question was about making
emulsions... you just weren't paying attention. (again!)

"I've been interested in making my own..."

Wern't you the one who expanded the subject away from the
needs of the poster?

The original post had these 2 questions:
1. Is their a component (bromide?) or procedure that will
make a hand poured dry plate at least as fast as wet
plates?

2.Is their a means of extending this shelf-life to a
couple of weeks or at least something more the a few
days?

You expanded the subject and yet I do not see a really
good response in there.

The initial emulsions before 1873 are not even to be
considered in my opinion. At the start there were wet
plates that were fasrter, later there fewer and fewer wet
plates that were faster that dry gelatin emulsions.

The question is about wet plate speed that one gets today
and dry plate (gelatin) that the poster is either going to
buy or is going to make. The answer to the question is
that he will be able to make dry plates faster than the
wet plates if he is serious about doing the work... abnd
he should not WORRY about the speed.

If he wants to go the commercial way, since they are
mostly chlorobromide (not all bromide as Ryuji seems to
belive) he may have to either sensitize and or digest for
more speed, (poster... this means cook your emulsion) or
use color sensitization methods. There are other methods
but we won't even get into those here. Details are
availible when needed but now the problem appears to be at
the "what if" level.

If he wants to make his own, then he shoud go the Silver
Bromoiodide route.

The second question is strange.
NO ONE should be having storage problems of just a few
days... with home made OR commercial emulsions...

the most likely source of cause of these problems are
1. too much heat during ANY stage of melting, coating,
storage, etc.

2.
Too much safelight exposure. or any UNsafelight exposure
(poor storage methods etc.)

3.
use of unsafe wrapping materials or methods, or other
sourches of contamination prior to or during processing.

"Is their a means of extending this
shelf-life to a couple of weeks or at least something more
the a few days?"

The answer is YES, be careful and use only safe materials
and procedures!

(If the emulsion IS for some reason void of stabilizer,
stabilizer can be added.)

IMHO, the poster shoud relax, do something, then come back
when he/she has a real, not a "what if" problem.

Ray Rogers

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Received on Mon Mar 7 04:45:29 2005