RE: physical developers

I worked a bit with chemical solarization which is a combination of of
chemical and physical development.

see Ed Buffaloe's excellent site:
http://unblinkingeye.com/Articles/Yurow/yurow.html

I wrote a little article on this technique in the last issue of PF

Best,

Cor

> -----Original Message-----
> From: MARTINM [mailto:martinm@SoftHome.net]
> Sent: Tuesday, August 24, 2004 8:32 AM
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: physical developers
>
>
> "Again, from what Dr. Henry found physical development has no
> advantages in
> practice. Although it is claimed ot produce extremely fine
> grain Henry found
> that it was no finer, and sometimes coarser, than D-76.
> It would probably be intresting to experiment with."
>
> For Lippmann emulsions physical developers may have some
> advantages though.
> They are able to produce grain sizes smaller than 10nm...
>
> Martin
>
>
> ----- Original Message -----
> From: "Richard Knoppow" <dickburk@ix.netcom.com>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Tuesday, August 24, 2004 7:51 AM
> Subject: Re: physical developers
>
>
> >
> >
> > -----Original Message-----
> > From: Bill William <iodideshi@yahoo.co.jp>
> > Sent: Aug 23, 2004 9:29 PM
> > To: alt-photo-process-l@sask.usask.ca
> > Subject: physical developers
> >
> > Speaking of physical developers, anyone here use them?
> >
> > Got any formulas / experience you would like to share?
> >
> > Ray
> >
> > __________________________________________________
> > I have no direct experience but will refer you to Richard
> Henry's famous
> book _Controls in Black and White Photography, second
> edition. This has
> gotten quite rare but some libraries may have it. In it Dr.
> Henry reports on
> some controlled tests using the O'dell formulas. His
> conclusions are that
> the claims made for it are not borne out in practice. Haist
> has a short
> section on physical developers in _Modern Photographic
> Processing_. For
> those not familiar with the term a physical developer is one
> that plates
> silver onto the development centers of the exposed halide
> particals rather
> than converting the halide to silver, a process known as chemical
> development. It is likely that some fine grain chemical
> developers have some
> contribution from solution physical development.
> > If a plain fixing bath is used it is actually possible
> to develop the
> latent image in fixed out film by means of a physical
> developer. This is
> mostly of academic interest but it is a demonstration of how
> the development
> specks produced by light remain in the gelatin even when the
> silver halide
> is removed. The sensitivity of the film is very much reduced,
> perhaps on the
> order of ten or twenty times when this process is used. I am
> away from my
> references now so am going on memory but I think this is
> correct at least as
> to order of magnitude.
> > Again, from what Dr. Henry found physical development has no
> advantages in practice. Although it is claimed ot produce
> extremely fine
> grain Henry found that it was no finer, and sometimes
> coarser, than D-76.
> > It would probably be intresting to experiment with.
> >
> >
> >
> >
> >
> > Richard Knoppow
> > dickburk@ix.netcom.com
> > Los Angeles, CA, USA
>
Received on Tue Aug 24 02:00:38 2004