21/01/2018: Today I recovered this blog post from an old database. Please note that I have not edited it, so it reflects my understanding of this topic in 2012. It does not fully reflect my current printing practice. The essential principles are correct though.
I have been exploring making ‘pure’ platinum prints (see some notes here), and I continue to be struck by the differences between platinum and palladium images.
I’d like to illustrate some of these differences by showing some test prints I made recently. The first three were made on Fabriano Artistico Extra White paper with the same printing parameters for each print. Before printing, the paper was pre-treated by soaking it in 1% oxalic acid for 10 minutes, which is a necessary step when preparing Fabriano Artistico for platinum/palladium printing.
Print 1 is a platinum/palladium print made with 1cc of the platinum salt and 4 drops of the palladium salt (this is currently my standard for warm toned platinum prints). This is, if I may say so, an exquisite print – actually it’s my reference print for this negative on Fabriano Artistico EW.
- “After Kertesz” – a Platinum Print from an 8″x10″ in-camera negative
Print 2 is the same as print 1, except that I omitted the palladium – i.e. it is a ‘pure’ platinum print. As you can see, there’s virtually no image present, and where there is an image (in the shadows) it’s only faint and grainy. It looks to me as if at least 95% of the platinum that I put into the coating has washed straight down the drain.
- Print 2: “After Kertesz” – a failed platinum print on Fabriano Artistico
Print 3 is the same as print 1, except that this time I omitted all the platinum and replaced it with distilled water (the extra water ensured that there was sufficient sensitiser to coat the paper). This print has virtually no palladium in it (only about 15% of what would be considered normal), but it has still produced a full and clear image (albeit one with no density in its shadows).
- Print 3: “After Kertesz” – a highly dilute palladium print on Fabriano Artistico
When looking at these three prints, I can only draw one conclusion: that the first print’s image is made almost entirely from palladium, with platinum simply adding a bit of extra depth to the shadows.
So what’s happening here?
Let’s look first at the awful platinum image. This, I believe, is dues to additives in brilliant white papers that stop the platinum image from forming. (It’s worth noting that this is not unique to Fabriano Artistico Extra White. I have also seen this result with Arches Platine and COT320 – two of the most popular papers for platinum/palladium printing.)
The only papers with which I have been able to get really good pure platinum prints are Ruscombe Mill‘s Buxton and Herschel papers, which are about as additive free as paper can be. (I have some evidence that normal Fabriano Artistico, not the Extra White variant, may also be able to produce a reasonable platinum print, but I haven’t yet made a good enough print to be confident about this.)
Print 4 is a pure platinum print from the same negative, but made on Buxton paper. This looks better in the original than in reproduction – a beautiful, delicate silvery look.
- Print 4: “After Kertesz” – a pure platinum print on Buxton paper
The second reason for the differences between these three prints is that palladium is far more vigorous than platinum. With any given combination of metal salts, exposure and developer, palladium will produce a stronger image. I estimate that palladium coated papers are perhaps one stop faster than platinum coated papers. Palladium also has a longer contrast range than platinum, so for any given combination of exposure and developer, the palladium highlights will be darker than the platinum highlights.
The effect of this extra vigour, is that if you are mixing anything more than tiny amounts of palladium with your platinum salts, then you will have to expose and regulate contrast primarily for the palladium. This means that your platinum image will be both underexposed and only visible in the shadows, which in turn means that your final image will be mostly palladium. (Perhaps this helps to explain why so many modern ‘platinum’ or ‘platinum/palladium’ prints are brown – which is the tell-tale signature of a palladium print.)
My conclusion is that if you want to make prints that contain a meaningful amount of platinum, then you need to do one or both of the following: (1) use a high quality paper, and (2) use a minimum amount of palladium. Alternatively, if you want to use a wider range of papers or to minimise cost, then stick to palladium prints because most of the platinum you add to the coating will be wasted anyway.