Re: Dry Plate Speed & Shelflife

> Plus, I'm asking your experience, not that of Glafkidès.

Ryuji, frankly, I am absolutely not keen on competing with your
semi-professional (non reduction sensitized) silver halide emulsion. I am
only interested in ultra-fine emulsions. And I certainly don't know for sure
whether the method described at http://cabd0.tripod.com/holograms/id3.html
will yield outstanding results on the very first attempt. That's why I spoke
of ADAPTING that method. E.g. in the context of "normal" photography the
sensitizing baths need to be adjusted - unless ultra-fine emulsions are
attempted. In addition I would definitely advocate the use of a different
dye. The above mentioned system mainly bases on a red-sensitive dye
(Pinacyanol). I guess that spectral wavelength range might be rather
inconvenient for most "normal" photography. Luckily that dye can be replaced
by an other cyanine dye, which is sensitive around 510nm, to green light
hence. The dye is Quinaldine Red (relatively easily available).
I assumed, given the long tradition of this kind of SH emulsion making
("bathing method") it fit well with the philosophy of alt.photography. I
guessed it would be silly to neglect more than one and a half century of
experience made by people around the world (from Talbot, Poitevin, Liesegang
till now) with different kinds of bathing methods. Having learnt many things
from reading the posts from alt.photo, I simply thought I might give back
something to the group. Anyway, I am convinced someone willing to take the
risk and experiment with that method, will ultimately succeed.

Martin

----- Original Message -----
From: "Ryuji Suzuki" <rs@AgX.st>
To: <alt-photo-process-l@sask.usask.ca>; <martinm@SoftHome.net>
Sent: Saturday, March 05, 2005 10:20 AM
Subject: Re: Dry Plate Speed & Shelflife

From: MARTINM <martinm@SoftHome.net>
Subject: Re: Dry Plate Speed & Shelflife
Date: Sat, 05 Mar 2005 09:47:01 +0100

> > In conventional emulsion, large grains refer to 1 micron or larger in
> > diameter. Can you make grains that big by bathing method?
>
> Have you read the paragraph I quoted from Glafkidès' book?

Yeah but that part didn't say grain diameter or photographic speed.
Plus, I'm asking your experience, not that of Glafkidès. By the way,
which edition and section was that paragraph taken from? (I have the
book somewhere.)

> > Can you speak in terms of lux seconds of exposure?
>
> Unfortunately, we have radiometric measures (W/sq cm). They can't be
> converted into photometric measures.

You can "measure" lux by using a reasonable photographic light meter.

> The method introduced by Glafkidès may produce layers in the 10 ASA
> area. If you added reduction sensitization, I guess you'd easily get
> 50 ASA.

Let me know when you get ASA 50. (Frankly I would be surprised if that
method produced ASA 5.)

--
Ryuji Suzuki
"Well, believing is all right, just don't let the wrong people know
what it's all about." (Bob Dylan, Need a Woman, 1982)