Troubleshooting help request: silver gelatine emulsion with homemade jellyfish gelatine

[stomolophus]

Hi,

Hoping someone might be able to assist with a project I'm trying to sort out. I'm trying to make a silver gelatine emulsion using my own homemade gelatine produced from jellyfish. So I've made some gelatine from salted preserved jellyfish. I haven't bloom tested it or anything, and it is quite a weak gel, but it otherwise looks and functions appropriately.

Using this gelatine, I'm following this recipe to create an emulsion: https://www.filmlabs.org/technical-section/shooting/a-simple-home-made-emulsion-recipe/. The changes I have made have included doubling the amount of gelatine in an attempt to compensate for its low strength (or at least as much I can accurately do so, it is difficult to get all of the water out of the gel once it's made in a home kitchen). I am also adding 2g of chrome alum at the end to try to harden it a bit.

I have followed this recipe prior using photo grade gelatine with good results, which makes me think my issues have to do with the gelatine itself. Unfortunately I have almost zero understanding of the underlying chemistry, which is what I'm hoping someone here might be able to help me with.

Here are some photos for discussion:

These are initial contact print tests under an enlarger on watercolour paper with four coats of gelatine. The thin dark piece in the middle of the row is 3 minutes in Dektol under normal room lighting; the darker contact prints were exposed at around 10 minutes under the enlarger wide open.

I also attempted to make some dry plates. This is one coat, 10 minutes exposed under normal room light and contact printed.

That was my best result, with the ones after going weird and bitty.

And another. Something odd that is common across all of the ways of coating, how many coats, etc. is that they typically look great in the developer, but once they go into the fix, the whole image goes a bit funny and seems to sort of...wash out? I don't really know how to describe it. This happens with rapid fix as well as sodium thiosulfate.

So my main issues are the bittyness that seems to be happening if that makes sense, and the weird fixer washout. All of the chemistry except for a bit of the gelatine is mixed with distilled water, but I am washing in tap water at the end.

Does anyone have a sense of how to make this a bit more functional, or at least as much as possible given the gelatine isn't meant for this purpose?

 

[RogerHyam]

Kudos for your craziness attempting something like this. I think you may need a zoology forum rather than a photographic one! Jellyfish are so far removed from the mammals that photographic gelatine is derived from I feel there has to be something fundamentally different with the collagen that occurs in them. The wikipedia page for collagen has a comparison table between fish and mammals showing the difference (https://en.wikipedia.org/wiki/Collagen#Biology) and these fish are presumably not only vertebrate fish but bony fish so much close to mammals than jellyfish. There is probably a table somewhere showing the difference with "lower" animals.

If nothing else Jellyfish have to remain soft and jelly like even in pretty cold sea water whilst mammals are always the same temperature and use collagen in tissues of different consistencies. The properties required seem quite different.

Could it simply be that the bloom strength of the gelatine isn't strong enough to bind the Silver Nitrate crystals in place? i.e. Jellyfish collagen is unsuitable for photography and there is nothing you can do about it.

What temperature does it melt at?

Have you tried washing the emulsion by noodling it and rinsing in cold water? The emulsion you make will be full of unreacted Potassium Bromide and Silver Nitrate. These are soluble in water whilst Silver Bromide is not. I don't have a logical reason for suggesting this other than it is what you must do to make dry plates. It might just wash out all your silver nitrate as well if the gelatine is so weak but there is a chance it will wash out the nasty stuff that is causing the issues and leave the silver. It might just waste another evening of your time!

Good luck and post again if you have more success.

 

[revdoc]

Some of your issues could be down to exposure. Unsensitised plates generally only respond to blue and UV light, and both room light and enlarger light tend to be lacking in those. I'd try exposing in daylight to see if the results are better. Start at an ISO of 0.1 and work upwards.

 

[M Carter]

And watch your processing temps - sometimes you have to cool things down if emulsion is lifting like that.

I've done mostly paper and canvas, but I've found hardener can make a big difference with adhesion, glyoxal or other. the main thing is really having a subbing layer that the emulsion can bond with well.

 

[stomolophus]

Hi all thanks for your replies! I was away for work last week and haven't been able to do any further tests.

I'll be back in the darkroom tomorrow and will be able to update my attempts. I think exposure is definitely an issue, and the lifting doesn't happen if the exposure is appropriate as far as I can tell. The emulsion will actually melt at room temperature if given long enough, which doesn't bode well either I suppose! Another thing I am going to try is making an emulsion from commercially available fish gelatine with a higher bloom strength as a comparison.

Will report back again in a couple of days!

 

[Nodda Duma]

You can also keep your dev and processing temps below room temp, and use a hardening fixer to strengthen the gelatin.

Control all your temperatures to be the same to reduce frilling.

 

[stomolophus]

So in a weird turn of events, the emulsion is totally fogged, and the bottle also bloated (suggesting the emulsion had gone off?). It smelled fine otherwise. I'll need to make another batch this week.

 

[AgX]

I follow this thread from its start, but still am wondering: why? Why jellyfish gelatin? Is it just curiosity or is there a special reason? Is jellyfish gelatin less un-vegan than pork or cow one, if this should be the reason?

 

[stomolophus]

I follow this thread from its start, but still am wondering: why? Why jellyfish gelatin? Is it just curiosity or is there a special reason? Is jellyfish gelatin less un-vegan than pork or cow one, if this should be the reason?

It is part of my PhD research! I am looking at a jellyfish fishery attached to a university project working to create jellyfish-gelatine-based food products. Creating/using the silver gelatine jellyfish emulsion offers a way to talk about representation and reproduction in this context; re: un-vegan...there will also be interesting discussions to be had in the write-up around cognition, intelligence, and ethics.

Unfortunately I have also fallen ill...the emulsion-making hasn't been super productive since the first tests. I'm hoping to get more gelatine made tomorrow as I've already rehydrated/de-salted the jellyfish.

 

[markjwyatt]

Look at Table1 here: https://journals.plos.org/plosone/article/file?id=10.1371/journal.pone.0253254&type=printable

Jelly fish gelatin (at least this sample) has low strength, low viscosity and low melting temperature compared to bovine gelatin. The biggest problem may be that it melts at room temperature (20.5 Deg. C), while bovine gelatin is not melted. Obviously you need to test your sample to see where it fits. Also clarity (actually turbidity) is higher.

This reference has Table 1 that shows some significant differences in some of the amino acid contents that may offer a clue (see especially Gly): http://www.ifrj.upm.edu.my/23 (02) 2016/(8).pdf

Of possible interest: https://www.researchgate.net/public...ical_Analysis_of_Gelatin_in_Photographic_Film
EDIT: Actually this last link is totally unscientific. I thought it contained some science and study of gelatin, but it is really more of an anti-meat essay. I leave it because I posted it, and some people did bring up ethics. My thoughts are if we are going to destroy a cow or other animal for meat, it makes sense not to waste any part of it.