Emulsion on XL surfaces - processing application instead of trays?

I want to create work with liquid emulsion on large stretched cotton/linen canvas surfaces (100cm+) and large sheets of washi paper, and wonder how to go about processing these. My processing trays can only take up to 50 x 70cm. I could get custom plastic trays built, but I wonder if anyone has any experience in applying the processing chemicals directly onto the exposed surface instead of tray processing?

I came across the below paragraph in an old darkroom book & it feels like the perfect solution... Any tips? How to get even application with a sponge etc?

Yeah, you could sponge the surface. Brushing would work as well. With media that can be rolled up and are sufficiently stiff to retain integrity (so not the washi, the canvas may work), you can also process them in a trough (a length of rain gutter with end caps for instance). Another option would be to spray the solutions onto the surface using a spray bottle. Evidently, wear a mask and protect your skin from the alkaline developer, and I'd use a spray bottle as opposed to a misting bottle to reduce the risk of breathing the solutions.

elise said:

How to get even application with a sponge etc?

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Yes, that's a concern, as would the potential for damage since you're working with a delicate emulsion. Definitely use hardener in the emulsion, that's for sure. Evenness is perhaps less of an issue than it may appear beforehand; the reason is you can essentially develop out the image, so any areas that are slow to catch up, will eventually catch up for the most part. Whether it'll be perfect, IDK, but I guess that the texture of the materials you propose to use will hide some of the potential issues anyway.

I'd just try some small sections to figure out methods that work well.

Not a direct answer to your question, but qs an inexpensive option closer to tray development, most home improvement stores sell clear plastic sheet that's intended for use as a vapor barrier. It's pretty thick stuff and you could pretty easily construct a temporary tray without needing to actually store a tray that size.

As far as direct application of developer goes, the only experience I have there is around my attempts at diffusion transfer (ala old school polaroid) where a thickened monobath is rolled out between a negative/positive. I imagine you could add some CMC (Carboxymethylcellulose) to your developer of choice and then apply it with a roller to get good even coverage rapidly. Intuitively that seems more delicate than a brush or sponge, but you'd have to test and see

I did prints. to 120x200 cm this way. The hard part is washing the print.