Re: DuPont Velour Black

----- Original Message -----
From: "Richard Knoppow" <dickburk@ix.netcom.com>
To: "MARTINM" <martinm@SoftHome.net>
Sent: Sunday, July 17, 2005 11:31 AM
Subject: Re: DuPont Velour Black

> Anti-foggant in the developer can get rid of some fog but I think there is
a limit. > As I understand it some age fof is due to a continuation of the
ripening process. > Substances are added to the emulsion to prevent this but
are not completely >effective. I don't know if this is a reversable
process.

You might try this:
prior to exposure - insert the emulsion in a gentle rehalogenating bleach
for one minute, rinse and dry.
On ultrafine silver bromide emulsions EDTA proofed do nicely - without
destroying spectral sensitization.
Ferric EDTA..............20g
KBr...........................10g
water...........................1L

Some emulsions may require additional re-activation for one minute in a 1%
ascorbic acid solution, tuned to pH 6.

Martin

> ----- Original Message -----
> From: "Richard Knoppow" <dickburk@ix.netcom.com>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Saturday, July 16, 2005 7:41 PM
> Subject: Re: DuPont Velour Black
>
> > Velour Black has been discontinued for decades. Its
> > possible that some might still be around but probably too
> > badly fogged for use.
>
> It might be possible to kill the fog and re-activate the emulsion...
>
> Martin
>
>
> Well, I don't know how to do this. Anti-foggant in the developer can get
rid of some fog but I think there is a limit. As I understand it some age
fof is due to a continuation of the ripening process. Substances are added
to the emulsion to prevent this but are not completely effective. I don't
know if this is a reversable process. I don't remember when DuPont
discontinued Defender products but it must have been very long ago. Some
papers seem to have a very long shelf life. I've used some Agfa papers which
still worked OK after twenty years but some Kodak papers went bad in four or
five. I have no idea of how well Defender papers resist age fog. If I ever
see any old papers at a sale I may try them, if the price for them as
collector's items is not too high.
>
>
>
> --
> Richard Knoppow
> dickburk@ix.netcom.com
> Los Angeles, CA, USA
Received on Mon Jul 18 03:29:05 2005