Platinum print latent image

bomzi · Feb 5, 2025

I'm a novice platinum print maker.
Am I overexposing my platinum prints? Images attached.
The latent image is not that different from the final print. And it doesnt change that much when I pour the developer.

These are prints made from Ilford Delta 100 4x5 negatives.
Arches Platine coated with Potassium Chloroplatinate (6 drops) with Ferris Oxalate (3 drops) and Ferric Oxalate + Potassium Chlorate (3 drops)
Exposed to the sun for 10 mins
Developed with Ammonium Citrate
Cleared with EDTA and Sodium Sulfite
washed in tap water

Thanks!

Alan9940 · Feb 5, 2025

Your method of working is different than mine, but in all my years of pt/pd printing I've never seen the latent image be that dark. After UV exposer, I can just barely make out the overall image with the dark areas being the most prominent. Development is immediate, but I leave it in for about 2 mins; the image will not noticeably change any further at this point.

koraks · Feb 5, 2025

bomzi said:
Arches Platine coated with Potassium Chloroplatinate (6 drops) with Ferris Oxalate (3 drops) and Ferric Oxalate + Potassium Chlorate (3 drops)
Exposed to the sun for 10 mins

Do you dry the sensitized paper before exposing it?

bomzi · Feb 5, 2025

koraks said:
Do you dry the sensitized paper before exposing it?

Yes, I let it dry for maybe 1/2 an hour inside a box which is inside a drawer. So I dont think its getting any extra light.
Here's another one.

Maybe I'm leaving it in the sun for too long?

koraks · Feb 5, 2025

bomzi said:
So I dont think its getting any extra light.

That's not why I asked. AFAIK if the paper is still moist during exposure, it'll print out more strongly, so the image you see before it goes into the developer will also be stronger.

dpurdy · Feb 5, 2025

I agree with Koraks that the moisture level of the paper has a big effect on the darkness of the blacks in the latent image. Personally I always dry my coated paper with a hair dryer until they are crackly dry and then rehumidify them with steam. I do this for consistency and for depth of black in the final print. Different types of paper might be different in this way also. I wouldn't worry so much about the latent image just the processed one.

Alan9940 · Feb 5, 2025

dpurdy said:
I agree with Koraks that the moisture level of the paper has a big effect on the darkness of the blacks in the latent image.

I agree regarding the depth of the blacks, but have you seen a latent image this dark following exposure? Maybe I simply misunderstand that the image on the left is what the print looks like before development?

With regard to residual moisture level in the paper prior to exposure, I've worked two ways: 1) coating the paper, then letting it dry in the dark until it has a "cold, limp" feel just before exposure, and 2) coating, drying with a hair dryer for a few mins, set aside in the dark until bone dry, then re-humidify in a chamber I built specifically for this task. In either case, my latent image following UV exposure is not this dark.

However, all that said the final print doesn't look bad (again, assuming the image on the right is the developed print.)

bomzi · Feb 5, 2025

Alan9940 said:
I agree regarding the depth of the blacks, but have you seen a latent image this dark following exposure? Maybe I simply misunderstand that the image on the left is what the print looks like before development?

With regard to residual moisture level in the paper prior to exposure, I've worked two ways: 1) coating the paper, then letting it dry in the dark until it has a "cold, limp" feel just before exposure, and 2) coating, drying with a hair dryer for a few mins, set aside in the dark until bone dry, then re-humidify in a chamber I built specifically for this task. In either case, my latent image following UV exposure is not this dark.

However, all that said the final print doesn't look bad (again, assuming the image on the right is the developed print.)

No you are correct Alan. The image on the left is prior to development.
I've attached another example. This one was made with a digital negative printed on Pictorico.

What I found interesting is that the highlights look blown out prior to development but they come back in nicely.

The coating felt dry to the touch but perhaps it wasnt that dry after all. I have a coated sheet that I was unable to use today (the sun set too quickly) so I'll leave it overnight and will use it tomorrow. Should definitely be dry by then! (although I imagine that leaving it for so long leads to other issues.)

koraks · Feb 5, 2025

bomzi said:
What I found interesting is that the highlights look blown out prior to development but they come back in nicely.

Yes, that happens with a number of partial-POP, partial-DOP processes. You see the same with e.g. Van Dyke brown or Kallitype. Only the deepest shadows print out, the midtones and highlights develop out.

bomzi said:
Should definitely be dry by then!

It depends also on ambient humidity; if you work in a very damp space, then the paper will reach a higher humidity equilibrium than under very dry conditions.

Alan9940 · Feb 5, 2025

This is a very interesting thread to me as I print from digital negatives, too, but have never seen a dark latent image as you've shown. Your latent image appears to be a completed print sans the clearing stages. Fascinating!

To be clear, you're using a developing out process vs a printing out process ala Pradip Malde / Mike Ware, correct? I just had a memory cell finally fire that made me recall that back when I was experimenting with the Malde/Ware platinotype that my prints looked more like yours prior to clearing. There is no "development" in this process, rather a series of clearing baths.

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