From: Sandy King (sanking@CLEMSON.EDU)
Date: 09/29/03-08:33:23 AM Z
Marek,
I would agree with you that a single drop of Na2 would increase the
contrast of the sensitizer quite a bit. However, it was not clear to
me that the single drop of platinum that Nick added was Na2. A single
drop of regular platinum solution would not change the contrast very
much at all. If I were to use the same sensitizer that Nick used in
my own working conditions the paper exposure scale would be fairly
high, about 1.6-1.8.
My own take on this, given the fact that Nick already knows a thing
or two about the variables of kallitype, is that his negative, for
whatever reason, is printing with more effective density range than
he reads with his color densitometer. I have verified to my own
satisfaction, and have had numerous exchanges of messages with others
who have also seen this, that some of the inks and pigments used in
printing digital negative have the same effect as stain density in
pyro negatives, that is they give a negative with greater effective
printing contrast than one would imagine based either on a visual
inspection or by reading with a densitometer.
Sandy
>Nick,
>This is stil a very contrasty emulsion (I assume you are using 20%
>solution of Na2PtCL6). 1 drop of Na2PtCL6 to 20 Pd wil gove you a definite
>contrast change.
>Marek
>
>> Re: PT/PD density/contrast/definitionEric, The odd thing about all this is
>> nothing about the environment is different, same old cold bath developer
>> and same 66%RH. The PD has been around for a while and the FO is new. I
>> get three tests from a 2x8 strip. My basic question has boiled down to
>> how I should change the ratio of PD to FO in this case? If you had a lack
>> of tonal range in a mix of equal parts of FO and PD how would you change
>> the ratio.
>>
>> Maybe I should redo the FO?
>>
>> Thanks for the info,
>>
>> N
>> ----- Original Message -----
>> From: Eric Neilsen
>> To: alt-photo-process-l@skyway.usask.ca
>> Sent: Sunday, September 28, 2003 5:41 PM
>> Subject: RE: PT/PD density/contrast/definition
>>
>>
>> Have you tried adding more PD in relation to your FO, i.e. 5 drops FO
>> and 7 drops PD? Or maybe even try coating 8 test strips worth of paper
>> and cutting it down after coating. How many prints do you make at 2" by
>> 8"? I would guess not very many. Size up trim down and try different RH
>> and see what happens to your test.
>>
>>
>>
>> Eric Neilsen Photography
>>
>> 4101 Commerce Street
>>
>> Suite 9
>>
>> Dallas, TX 75226
>>
>> http://e.neilsen.home.att.net
>>
>> http://ericneilsenphotography.com
>>
>>
>>
>> -----Original Message-----
>> From: Nick Makris [mailto:nick@mcn.org]
>> Sent: Sunday, September 28, 2003 12:36 PM
>> To: alt-photo-process-l@sask.usask.ca
>> Subject: Re: PT/PD density/contrast/definition
>>
>>
>>
>> Sandy and all, I tried the method of reducing the exposure by half, and
>> here are the results:
>>
>>
>>
>> I now have seperation between 15% and 90%.
>>
>> The blackest black is now not quite black enough.
>>
>> The print density range was expanded slightly, but as expected, work
>> needs to be done to bring in the highlights and there is still an
>> indication that the exposure is too long.
>>
>> All of this indicates to me (this is a question) that the tonal range of
>> the sensitiser in lacking, but I have no idea about what to do next.
>> The mix is currently 5FO, 5PD and 1PT for a small 2"X8" test strip. The
>> PT is supposed to be adding some contrast to the sensitiser, but the
>> results of the reduction in the exposure. If I remove the PT it will
>> reduce the contrast even further.
>>
>>
>>
>> Which direction does one go when the negative is contrasty and the
>> sensitiser is using just equal parts of FO & PD? If I make the
>> sensitiser any less contrasy or reduce the contrast of the negative the
>> print will surely be useless.
>>
>>
>>
>> Still confused and in need of helllllppppp.
>>
>>
>>
>> Many thanks,
>>
>>
>>
>> Nick
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> ----- Original Message -----
>>
>> From: Sandy King
> >
>> To: alt-photo-process-l@skyway.usask.ca
>>
>> Sent: Saturday, September 27, 2003 5:43 PM
>>
>> Subject: Re: PT/PD density/contrast/definition
>>
>>
>>
>> A few thoughts.
>>
>>
>>
>>
>>
>> First, the effective printing density range may be greater in the UV
>> than what you measure with your color analyzer. This is certainly the
>> case in my work with the pigmented inks of the Epson 2000P on
>> Pictorico where the difference between measured density range between
>> a Visual and UV reading is over log 0.30. So it is possible that the
>> effective DR of your negative is really closer to 2.0 or 2.1 than 1.7.
>>
>>
>>
>> Second, your note that the dark steps loose separation beginning at
>> about 30% suggests that you have overexposed the negative. When we
>> print we must expose for the dark values, and then take steps as
>> necessary to control contrast in the highlights.
>>
>>
>>
>> In any event the result you describe is consistent with slight
>> over-exposure and a negative that has too much contrast to handle the
>> sensitizer you used.
>>
>>
>>
>> Sandy
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> Ok (BTW, please correct any questionable assumption made herein), I
>> have a digital step wedge negative with a base density reading of
>> .39 and a highlight density of 2.2 (being a complete neophyte, I
>> might have these reversed) which equals a difference of 1.81. As
>> Sandy kindly pointed out recently, you also have to make an small
>> adjustment which makes this neg have a density range of
>> approximately 1.7. As has been discussed recently, 1.7 should be a
>> good density for a normal negative when doing PT/PD. Also, there is
>> good separation between all the steps when viewed and tested for
>> density on my old color analyzer, now new densitometer.
>>
>>
>>
>> I used equal amounts of FO (freshly mixed at 27% as I have done many
>> times) & PD (older) and a single drop of PT (which has rendered the
>> desired color) for a total of 11 drops on a proper sized image
>> opening. My rough calculation is .48 drops per square inch of image
>> area on Cranes Platinotype when using a glass rod.
>>
>>
>>
>> The resulting test print indicates that I have arrived at nearly the
>> proper exposure because the highlights have density up to the proper
>> point on the steps and the highlights have cleared properly. And,
>> the black is as black as I could ask for.
>>
>>
>>
>> On the other hand, the dark steps loose separation beginning at 30%.
>>
>>
>>
>> Ed Stander tested this substrate and found it to have an identical
>> association between visible and UV light blockage in the entire
>> range - Our thanks to and a quote from Ed:
>>
>>
>>
>> "The film blocks a proportion of received UV and Visible light
>> equally across the board. There are no real peaks or troughs in the
>> transmission curves. Having said this, the blockage is as follows:
>> The waxed film blocks 1/2 of the UV falling on it, while the unwaxed
>> film blocks 3/4 of the UV it receives. These values (amazingly
>> enough) are nearly exact at 360 - 400 nm."
>>
>>
>>
>> I infer from the above statement that if I use the film unwaxed, I
>> will add a stop of exposure to my established time plus compensation
>> for the base. In the case above, the exposure is just more than
>> twice the length of the exposure for a Lightjet neg that I have
>> printed successfully many times - as expected.
>>
>>
>>
>> So, where am I? Well that's what this post is for - I don't have
>> any real direction to follow here and I'm looking for some input.
>>
>>
>>
>> Could the ink blockage for the UV not be linear to the visible light
>> (my enlarger) that I used to test the density?
>>
>>
>>
>> Could I have miscalculated the density (complete babe in the woods
>> here) and in reality the neg is more/less contrasty than I'm
>> thinking it is?
>>
>>
>>
>> Could some of chemicals be outdated? Potasium Oxylate (cold bath)
>> which as I understand it is better as it gets older (I also tried
>> some unused), freshly mixed Ferric Oxylate and I can't believe that
>> the EDTA has any bearing here.
>>
>>
> >
>> Could the single drop of PT be enough to increase the contrast of
>> the print from an already ok (read that I'm assuming a proper
>> contrast for PT/PD) negative?
>>
>>
>>
>> I'm sure to be embarrassed when the simple answer is arrrived at and
>> I promise to report.
>>
>>
>>
>> Appreciate your thoughts,
>>
>>
>>
>> Nick
>>
>>
>>
>>
>>
>>
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