Re: Dry Plate Speed & Shelflife

> 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? A quick
translation from http://babelfish.altavista.com/ might do the job.

> What's your definition of ultrafine?

Uniform grains, smaller than 30nm.

> Modern emulsion chemists have a list
> of chemicals that can be used to inhibit growth of grains.

That's a bit of a grey area. Curiously, despite of heavy use of grain growth
inhibing agents, big players like Kodak, Agfa,
Ilford, Konica failed to produce such ultrafine emulsions.

> 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.

> If you are saying you can make very usable plates of ASA speed 10-50
> by bathing method, I would like to see how.

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.

Martin

----- Original Message -----
From: "Ryuji Suzuki" <rs@AgX.st>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Friday, March 04, 2005 3:59 PM
Subject: Re: Dry Plate Speed & Shelflife

> From: MARTINM <martinm@SoftHome.net>
> Subject: Re: Dry Plate Speed & Shelflife
> Date: Fri, 04 Mar 2005 09:18:41 +0100
>
> > I don't see any particular difficulties with that.
>
> In conventional emulsion, large grains refer to 1 micron or larger in
> diameter. Can you make grains that big by bathing method? Did you try
> it?
>
> > For the making of ultra-fine SH emulsions the challenge consists in
> > forming very small grains and keeping them small.
>
> What's your definition of ultrafine?
>
> I described a couple of ways you can do this with various grain growth
> inhibitors in my previous email. Modern emulsion chemists have a list
> of chemicals that can be used to inhibit growth of grains. They also
> have a much better understanding of how to control growth, because a
> lot on this had been studied after Berry's model.
>
> > I have at least one paper that indicates a connection between HIRF and
> > reduction sensitization...
>
> HIRF is commonly dealt with electron trap (like iridium) doping and
> gold sensitization. Gold alone is pretty effective. Reduction may
> increase or decrease HIRF, depending on some factors not yet well
> understood.
>
> > Probably not. It has been a couple of years since the last time I
> > used an enlarger, but I believe to have had access to a 150 W (= 150
> > 000 mW) light bulb then. Optical losses run high in both cases. Even
> > considering the large bandwidth (and the large part wasted in form
> > of heat) of an enlarger's light source, I still have to get along
> > with my few milliwatts (per cm/2) only...
>
> Can you speak in terms of lux seconds of exposure? My enlarger has
> 150W bulb but with a negative in place, I only get a fraction of a lux
> at midtone of the image when projecting an 8x10 area.
>
> > Speaking of SH emulsion making, I just wanted to point to the
> > possibility of reaching the same goal by different means.
>
> If you are saying you can make very usable plates of ASA speed 10-50
> by bathing method, I would like to see how.
>
> --
> 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)
Received on Sat Mar 5 02:47:30 2005