mmatusz@pdq.net
Date: 09/29/03-07:59:45 AM Z
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
>
>
>
>
>
>
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>
>
>
> 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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