Digital BW, The Print

Very interesting and good to know Mark. Ilford also makes a warm tone paper 
and I suspect that it doesn't contain an OBA, but I'm not sure if it's 
available for digital exposure and machine processing.

On another note, did you ever hear of a neutral toner which was made by Agfa 
called Sistan? Supposedly it did the same job as selenium toner in that it 
stabilized the free silver ions left in the emulsion after processing but it 
didn't change the color of the print.


-----Original Message----- 
From: Mark
Sent: Tuesday, April 23, 2013 10:45 AM
To: DigitalBlackandWhiteThePrint@yahoogroups.com
Subject: Re: [Digital BW] Digital Silver Gelatin Print light fastness 
results



--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "John Castronovo" 
<jc@...> wrote:
>
> Which of course begs the question whether or not traditional silver halide
> paper exposed with an enlarger and hand tray developed would fare much
> better than this new short exposure digital paper which was probably 
> rapidly
> processed in a machine.

The OBA content is responsible for these results not the fact that the paper 
was sensitized for the spectral output of the laser and for high intensity 
short exposure times. These prints were  indeed machined processed to begin 
with for develop, rinse, and fix, but then given additional tray processing 
for those that were toned, plus extended washing by tray or "archival" wash 
unit for all samples.

As long as a B&W silver halide paper contains OBAs (and many have for over 
five decades now), the delicate initial hue and chroma of the image depends 
on a hybrid system where the image bearing particles may be exceptionally 
stable but the OBA dyes contributing to the color of the white paper, image 
highlights, and even mid tones are much more fugitive.

The surprise for me personally was that the swellable polymer coating (i.e, 
the photographic gelatin) did not appreciably seem to protect the OBAs from 
fading in either of these paper types any more than we see for many 
microporous  inkjet media. This should be the "take home" message for any 
collectors, curators, conservators,etc. who want to preserve the artist's 
original work in pristine condition for as long as possible. If the paper 
has moderate or high OBA content, one needs to regard the print as not very 
lightfast even when the image forming materials themselves are highly fade 
resistant, e.g. pure carbon pigment, sepia toned silver particles, etc.

cheers,
Mark
http://www.aardenburg-imaging.com



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