>In-Reply-To: <960507092423_101522.2625_IHK79-6@CompuServe.COM>
>
>> While regarding XP2 as a great film for the purpose for which it is made,
as the
>> film negative has an overall violet tone, I had always assumed that it
would not
>> be a good film to use to make contact prints when the light sensitive
emulsion
>> of the putative print is restricted in sensitivity to the violet end of the
>> spectrum.
>>
>> Terry King
>
>Terry, I think you are getting confused here. Properly processed XP2 negs
>have a 'slight' purple tint to the film base (definitely NOT violet). It can
>actually be completely washed out if it was a problem - but I don't think it
>should be. (It washes out more easily if you increase the time in the bleach
>fix - excessive purple is a sign of either exhausted blix or inadequate
>washing or both - as in the case of my local minilab)
>I can easily produce negs with XP2 that print well on Grade 1 paper - or
>softer - there are no problems with getting the kind of contrast appropriate
>for most processes. I see no reason why is shouldn't produce great results
>in platinum etc - as it can in silver.
>
Yes, the film base does indeed have a slight tinge to it and the tinge varies
depending on how the film was developed. But, I don't think that is the
problem since the tinge is even (ie adds to the overall density) and is
usually faint.
I think that something more subtle is going on.
Remember in XP2 that the image is formed in the same way that a colour image
is formed,
that is though the use of colour-couplers. Also, the silver is removed in the
bleach step so what you have is esentially a silver-less image formed of
"dye clouds".
Developed silver grains in conventional B&W films are solid particles that
are opaque to all wavelengths of light (ie wavelengths which are useful in
our image making. Don't ever remember reading about this though, but I have
managed to survive 40+ years without
having this notion challenged yet. I hope I'm on solid ground here with this
statement).
However, the dye molecules that are formed in the colour-coupling process
are complex and rather large molecules if my recollection about them is
still correct.
(as a side note, compared to molecularly simpler dyes, like azo based dyes
(eg Ciba/Ilfo Chrome), these large and complex molecules have a greater
tendency to breakdown at different rates which results in fading and colour
shifts in time). And, unlike a developed silver grain has a definite, and
measurable, absorption/transmission characteristics that varies with the
wavelength of light. For conventional silver-based black and white and
colour paper XP2 works very well.
However, from my limited investigations (a weekend 2 years ago, XP2 neg,
Palladium paper) I was not able to produce an image having more than 3 or
middle tones in it. A comparable looking TMax negative printed at the same
time showed a full range of tones.
After that weekend, I stopped using XP2 to contact print my Palladium prints.
I can only speculate that the XP2 image "dye clouds" were too transparent to
the UV region of light that the coated Palladium paper is sensitive to.
Can anyone confirm my suspicion? I have lots of XP2 negatives that I'd love
to print
directly without making silver based copy negatives. Has anyone obtained a
full tonal
range in Pt/Pd printing using XP2 as a negative?
Robert Hudyma, Email: rhudyma@idirect.com,
Semi-Tech Microelectronics, 131 McNabb Street, Markham Ontario Canada, L3R 5V7