[pure-silver] Re: VC printing equipment Was: Replacement for Bromofort paper;

----- Original Message ----- 
From: "Dave Valvo" <dvalvo@xxxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, December 24, 2004 9:12 AM
Subject: [pure-silver] Re: VC printing equipment Was: 
Replacement for Bromofort paper;


> J.R.
> I have been on this band wagon before touting the bad 
> features of the Thomas
> safelight.  Others have claimed they have no problems with 
> it.  Issue with
> the safelight is NOT fog but rather contrast changes. >
> I seem to recall 80CCY and 40CCG will bring a cold light 
> head to std white
> light.  Can't find my notes right now.  Maybe someone else 
> out there has
> better memory.
>

 Snipping here and further along....

    The Kodak safelight test booklet is still available on 
the Kodak web site in PDF form.
Do a search for K-4.

    The yellow filters will shift the spectrum of "blue" 
cold light heads so that grade 2 filters will print about 
the right contrast but the range and spacing of contrast 
grades with other filters will not be right. One end of the 
contrast range (I've forgotten which end) is severely 
compressed. Blue cold light heads are really not suitable 
for VC printing. There are newer cold light lamps with 
phosphors designed to mimic tungsten light. They will work 
with VC filters but, again, there is some loss of range of 
contrast adjustment and some distortion of the grade 
spacing. It seems to me that Kodak at one time showed the 
effect of using cold light on VC contrast in some 
publication, I think it was in a book with a title like 
"Making Good Prints with Kodak Paper". I have this somewhere 
and will try to find it.


> All the Kodak VC papers are designed to be insensitive to 
> developer.  That's
> what makes them so robust and reproducible batch to batch. 
> What I mean is
> as a developer gets exhausted the Kodak papers will 
> continue to perform
> well.  Unfortunately that means for those that like to 
> pull a print early
> will have reduced sensitivity.   Low contrast developers 
> vs Dektol is a
> different story.  The papers will respond well the them. 
> Photographers
> should instead control exposure and contrast etc on the 
> enlarger....not in
> the developer.
>
   I don't think developer will affect the contrast of 
printing paper much.So called low contrast developers, like 
Kodak Selectol Soft, seem only to take longer to reach the 
same shadow density as a standard developer like Dektol. 
I've never seen proper H&D curves for a paper in different 
developers so I could be wrong about this.
  All Kodak VC papers, and most other manufacturer's RC 
papers, have developer contained in a layer under the 
emulsion or mixed with the emulsion for the purpose of 
making the papers usable with rapid access machines of the 
"activation" type. These machines use an alkaline solution 
in place of a complete developer. The activator combines 
with the developer in the paper to form a complete 
developer. Since new developer is brought in with each print 
the life of the activator solution is very long. The 
disadvantage is that Dmax is lower than when a standard 
developer is used. The developer in the paper tends to mask 
differences in complete developers but extends their lives.

> Kodak Polymax Fine Art should have the lowest contrast 
> available of any
> fiber base paper sold today.   Best LER I was able to get 
> on my Zone VI cold
> light head was 1.65 which is like a contrast grade - .5. 
> Paper will go to
> a -1.5 contrast (if there was such a thing) or LER or 2.00 
> on a Saunders
> 4500 or VCCE. I don't know of any other paper that will go 
> that low in
> contrast.  And that is in Dektol.  Selectol Soft is 
> unknown.  Send me your
> email address and ask for the chart I have with this paper 
> on various
> enlargers.
>
> Dave

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx

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