IME - putting all other factors aside... - thin papers usually give higher dmax than thick ones.
Could be due the fact that:
Thin paper can't soak all the sensitizer due less empty space (per constant area) in its stucture, keeping more of the sensitizer in its upper layers (which is what we actually need), therefore giving better dmax. Thick paper will soak the sensitizer more deeply (where it doesn't fulfill our needs - leaving less of it in its upper layers), therefore give weaker dmax. That means, we'll have more sensitizer per paper volume with thin papers, resulting in higher dmax - keeping coating solution volume per area constant...
Just some food for thought.
P.S. I'm not saying we need sensitizer "on" the paper (that will wash down the drain in processing steps), we need it "in" the upper layers of the paper!
Originally Posted by Ian Leake
Last edited by Loris Medici; 07-14-2010 at 03:37 AM. Click to view previous post history.
Reason: Did some formatting...
With Pt/Pd, you are absolutely correct. OTOH, depending on paper type, the opposite may take place with Silver Halide in Gelatin.
I'd speculate that it's more about the rate at which the paper absorbs coating rather than its thickness per se. For example Buxton (thin paper) absorbs the coating quite easily (and it can absorb a lot of it if you want it to), whilst Arches Platine (thick paper) tends to keep the coating on the surface.
Ian, I'm more interested in why you asked the question.
I was given an exquisite Palladium print on Monday, we compared it to a Jorge Gastreano original, and close by where Fay Godwin & John Blakemore originals as well.
The Dmax of Jorge's Platinum print and the Palladium print aren't visually much different but the tonality is.
Back in the late 80's I remember discussing with Fay Godwin going on a Platinum/Palladium workshop, we both decided not to for similar reasons at that time, mainly volume of work. Also a distraction from ongoing projects.
I'm off to the South of Turkey to learn Plat/Palladium printing end of the month
Last edited by Ian Grant; 07-14-2010 at 03:54 PM. Click to view previous post history.
I think print color will have a big effect here too. Warmer tones with equal reflection density are going to look less dense than more neutral tones.
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Hi Ian. I have to admit that I'm not really that interested from an aesthetic perspective, but it's an interesting technical challenge.
Originally Posted by Ian Grant
Personally I like using the soft muted tones, but sometimes I have a negative that needs to have plenty of darkness and shadows. My challenge is that although I can now print as black or blacker than all the reference prints I own, I feel that I should be able to go further. So that's why I'm interested in what other contemporary printers can acheive.
I suspect that I'm close to the limit of what can be achieved with Buxton. The deep blacks that I've seen on prints by Irving Penn, Studio 31 and Salto have been on heavier/whiter/smoother paper. That being said, I've also found some interesting ideas to explore by reading nineteenth century sources.
I've primarily switched over to the Dichro method for contrast control; and am wondering if the expansion of contrast achieved thru higher quantity of Potassium Dichromate in developer would also increase the potential DMax? Also would temperature of developer affect DMax? It seems that when I use hot PO the DMax looks stronger, but I don't have means of testing this
Btw, Ian L., your book has been very helpful.
Last edited by doughowk; 07-14-2010 at 06:23 PM. Click to view previous post history.
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I don't think that the dichromate has an effect on Dmax (although I've not tested this). As I understand it, the dichromate does most of its work in the highlights.
Originally Posted by doughowk
I switched to room temperature developer some time ago on health grounds. After long printing sessions I was getting big headaches which I blamed on the amount of Potassium Oxalate which had evaporated into the air. I know of some other printers who got flu-like symptoms from this. I've not had any problems with room temperature PO.
That said, heating the developer definitely warms the tones and has other subtle effects too.
Both of these theories are simple to test. I'll do this when I'm printing next, and report back.
And thanks for your feedback on my book, Doug. My aim was to write a non-technical guide to Pt/Pd printing, and I'm glad people are finding it useful.
I was testing the differences between Platine and Fabriano Extra white tonight, both single and double coating
Double coated Platine was 1.4 unwaxed, and 1.51 waxed. Single coated waxed was 1.4ish
Double coated Fabriano was topped out around 1.3 unwaxed, and 1.34 waxed. single coated was just rubbish. Think I am having issues with residual oxalic acid in the Fabriano after pretreating it. It smells like chemicals and the surface is very rough/dusty feeling.
I asked this in another thread, but does anyone know what the sizing on platine is, or how it can be replicated on something like Fabriano Extra White?
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Could be (a.) not enough acidification or (b.) residual spiky calcium oxalate crystals affecting the surface qualities or (c.) both...
Originally Posted by Richard Boutwell
I left oxalic acid / Artistico combination because it was giving me a rough / gritty surface (coating with a puddle pusher / glass rod) and never turned back to it - for any paper! If not intimidated, just try dilute HCl (30ml 30-35% into 1000ml, or similar end dilution from weaker concentrations) and see if it works better for you...
Last edited by Loris Medici; 07-16-2010 at 04:35 AM. Click to view previous post history.
Reason: Fixed few typos and added a clarification.