Liquid light emulsion: thicker application and / or multiple applications

[sjg2000]

Hi everyone. I'm wondering two things:

1. if it would be possible to apply the emulsion thickly to the paper, let it dry thickly, expose and process without everything just washing away/coming off the paper. I'm trying to experiment with relief (visible after dry down) if possible. I know you can achieve this with carbon printing, but is it possible with liquid emulsion? If I applied it thickly (say, I didn't heat it up as warm so it didn't melt as much, and applied it to paper in a thick concentrate) and exposed for a long time, after processing would I get a thicker deposit of metallic silver? Or would most of it just wash away?

2. If its possible to take a finished print and apply liquid emulsion onto it again, re expose, re process. Or would I need to size the area with clear gelatine first?

Both of these questions would pertain to small select areas, not an entire sheet of thick emulsion application.

Thank you!

 

[koraks]

Welcome aboard @sjg2000 ! (I think we've been in touch over email recently; it's nice to see you here!)

I'm trying to experiment with relief (visible after dry down) if possible. I know you can achieve this with carbon printing, but is it possible with liquid emulsion?

Not really. Keep in mind that a silver halide emulsion remains in place after application, other than a carbon transfer print, which is made by selectively washing away the gelatin. This does not happen with silver halide; all the gelatin remains in place. What is removed, is only the undeveloped silver halide itself, but this does not affect the thickness of the emulsion. So there's in principle no relief.

I say 'in principle' because there's one caveat: that of a tanning developer (at least in B&W). 'Pyro' developers (like PMK, Pyrocat, 510 Pyro, Moersch Tannol etc.) also harden the gelatin as a side-effect of development; i.e. the emulsion hardens where development of the silver image takes place. Hardened gelatin shrinks a little, and this results in a very minor relief. However, this is so minor that it's generally only visible on a very smooth substrate, like regular film or glass. On paper, it will be overpowered by the texture of the paper itself (even if it's a smooth, hot-pressed paper).

It's theoretically possible to coat a gelatin layer so thick and then develop it with a tanning developer that the relief shows. But I doubt it will work in practice.

However...the tanning has another side-effect: the gelatin is rendered insoluble. So you could take a non-hardened silver gelatin emulsion, develop the image with a tanning developer and then wash away the unhardened gelatin in a warm water bath. This is in fact exactly the approach that was/is used for making the matrices for dye transfer printing. Whether you will get relief that's visible on paper - I really doubt it to be honest. It takes a heck of a thick gelatin layer to get a visible relief when dry, on paper.

If you want to create a visible relief using gelatin, I would consider using an approach as done in e.g. oil printing, where a clear gelatin (pigment could be added to it) is hardened selectively through a negative (contact printed) using UV light. This can be done also with e.g. ferric ammonium citrate (which is also used for cyanotype).

If its possible to take a finished print and apply liquid emulsion onto it again, re expose, re process.

Yes, this should work fine!