So I've seen a lot of discussions where agar agar is mentioned as a potential thing that could work in place of gelatin, and I'll completely side step the huge distraction that tends to come up with this topic by saying that my sole reason to want to avoid gelatin is that it is very annoying to work with.
Agar agar seems to surprisingly have quite a bit going for it as a potential replacement for gelatin in emulsion making:
* It seems to be more porous than gelatin. A simple test with a silver chloride emulsion "lump" thrown into developer for 2 minutes resulted in a dark line about 1mm from the surface, when I broke the lump open. A ~6mm thick lump of silver chloride become about 90% clear in TF-5 fixer, after 5 minutes. This would mean a thicker coating could be practical
* "damp" processing of agar agar emulsions is possible. As soon as it is cooled to room temp it can be exposed and processed, it will not melt, even in hot solutions which are below its melting point. Note that "damp" processing is subject to finger prints and smudging since it is still soft, but otherwise could be a very interesting process tool that would enable rapid coating and processing, similar to wet plate processing
* Alcohol seems to be more useful for reducing bubbles in the emulsion and thinning it out without making it impossible to set
* It has no problem sticking to the few of the papers I tried, but is also more resistant to soaking through the paper.
I floated a piece of dry platinum paper on the surface of the emulsion and let it sit there gently poking it until the paper started to curl up, I then lifted it from one end and let it drip from one corner. Aside from it being too thick at that corner, the coating appeared to be sufficiently thin, uniform, and pliable, with no issues once dry. It appears to be a more "pearl" style finish than hand coated gelatin. I also tried a few other coating methods and the only one that could have potential is a coating rod. If floating is a reasonable coating method, it'd honestly be preferably to me but floating with gelatin emulsions is practically impossible (soaks through paper too easily, and gets onto back too easily)
Anyway, I've seen a ton of topics mention agar agar, including the great PE claiming it had been researched by Kodak, but determined unsuitable. The biggest annoyance I see is just how hot the emulsion must be to keep it liquid, which also means more evaporation. However the relatively high setting temp and rapidness of setting is I think an extremely useful thing to consider.
Either way, I haven't made a "real" emulsion yet. I've only confirmed that the core properties of it seem promising. It keeps silver chloride suspended, does not directly react with silver nitrate, is compatible with acidic pH and alcohol, is porous enough for developing and fixing, sticks to paper without soaking through, and is not too brittle when coated on paper.
Has anyone actually gone through the steps of trying to form and coat a real silver halide emulsion using agar agar? What were your experiences? And please please please, lets avoid the whole"V" word that always comes up when this is discussed. I only care about avoiding the annoyance of working with gelatin and its long dry/set time...
Agar agar seems to surprisingly have quite a bit going for it as a potential replacement for gelatin in emulsion making:
* It seems to be more porous than gelatin. A simple test with a silver chloride emulsion "lump" thrown into developer for 2 minutes resulted in a dark line about 1mm from the surface, when I broke the lump open. A ~6mm thick lump of silver chloride become about 90% clear in TF-5 fixer, after 5 minutes. This would mean a thicker coating could be practical
* "damp" processing of agar agar emulsions is possible. As soon as it is cooled to room temp it can be exposed and processed, it will not melt, even in hot solutions which are below its melting point. Note that "damp" processing is subject to finger prints and smudging since it is still soft, but otherwise could be a very interesting process tool that would enable rapid coating and processing, similar to wet plate processing
* Alcohol seems to be more useful for reducing bubbles in the emulsion and thinning it out without making it impossible to set
* It has no problem sticking to the few of the papers I tried, but is also more resistant to soaking through the paper.
I floated a piece of dry platinum paper on the surface of the emulsion and let it sit there gently poking it until the paper started to curl up, I then lifted it from one end and let it drip from one corner. Aside from it being too thick at that corner, the coating appeared to be sufficiently thin, uniform, and pliable, with no issues once dry. It appears to be a more "pearl" style finish than hand coated gelatin. I also tried a few other coating methods and the only one that could have potential is a coating rod. If floating is a reasonable coating method, it'd honestly be preferably to me but floating with gelatin emulsions is practically impossible (soaks through paper too easily, and gets onto back too easily)
Anyway, I've seen a ton of topics mention agar agar, including the great PE claiming it had been researched by Kodak, but determined unsuitable. The biggest annoyance I see is just how hot the emulsion must be to keep it liquid, which also means more evaporation. However the relatively high setting temp and rapidness of setting is I think an extremely useful thing to consider.
Either way, I haven't made a "real" emulsion yet. I've only confirmed that the core properties of it seem promising. It keeps silver chloride suspended, does not directly react with silver nitrate, is compatible with acidic pH and alcohol, is porous enough for developing and fixing, sticks to paper without soaking through, and is not too brittle when coated on paper.
Has anyone actually gone through the steps of trying to form and coat a real silver halide emulsion using agar agar? What were your experiences? And please please please, lets avoid the whole"V" word that always comes up when this is discussed. I only care about avoiding the annoyance of working with gelatin and its long dry/set time...