Several textbooks show the change in dimension of gelatin during silver development. Unfortunately, all gelatin changes during development and forms cracks and shrinks (or expands).
PE
Well, since I have been addicted to various alt processes I am accustomed to high failure rates and plodding thru problems. In an odd way that is part of the fun.
But after I get an image on the factory plates, I wanted to try out making my own emulsion so I could make bigger plates. The pdf files Chris got from Hans have the recipe & procedure for making the fine grain emulsion. Your input, PE, would be immensely valuable. If you would like I can forward the files to you.
Yes, those are colloidal developers. Shrinkage is virtually absent, since no material is lost by the development.
Thanks, I have spent quite a bit of time reading on the holography forums Lippman section ( including your posts ) and there was lots of info there.
Would the pyro formula I have come across in several places be a colloidal developer? I could not decide if the GP-2 or pyro developer would give me the best chance of success.
Well, since I have been addicted to various alt processes I am accustomed to high failure rates and plodding thru problems. In an odd way that is part of the fun.
But after I get an image on the factory plates, I wanted to try out making my own emulsion so I could make bigger plates. The pdf files Chris got from Hans have the recipe & procedure for making the fine grain emulsion. Your input, PE, would be immensely valuable. If you would like I can forward the files to you.
I would be happy to help in any way, but I am not sure what I can do for you as I have never worked with Lippmann emulsions.
Hey, thanks for everybody's input. Especially the holo links.
What factors go into successful developing, that is, how can you avoid shrinkage? (no jokes necessary.... )
Is it temperature dependent, agitation, chemical, etc.? Lemme guess, all of the above! I wonder what the success rate is.
So here's a question... if you used mercury, would the shrinkage problem be minimized? Why must one use mercury? I guess it's because the mirror has to actually be in contact with the emulsion? So just sandwiching a mirror wouldn't work I suppose.
For what it's worth, making emulsions is way out of my league at the moment; I'll stick with the limitations of the available plates.
Lastly, could someone explain this sentence.... "The Slavich [PFG-03c] emulsion requires pre-development hardening in a formaldehyde solution." Is this the fogging that R Shaffer was referring to??
BTW: Lippmann plates can be projected, which to me seems like one of the most practical ways to display. It requires an aphengescope type projector (basically an opaque projector as far as I can tell). Here is a book link that describes it.... http://books.google.com/books?id=pqk...escope&f=false
Hydroquinone and HQ related developing agents cause micro cracks and shrinkage more than most other developing agents. Any tanning developer would cause this same type of effect to some degree, on a micro scale.
Prehardening with formalin or the like helps prevent such micro cracks and shrinkage.
I would be happy to help in any way, but I am not sure what I can do for you as I have never worked with Lippmann emulsions.
PE
Thanks,
The emulsion is down the road, but I have attached an excerpt from
"The True Colour of Photography by Hans Bjelkhagen & Darran PM Green"
that has the process & formula for the emulsion if your curious.
That makes sense, thanks for the input. Is formalin easily obtained for this purpose?
Here is a directory on Colin Kaminski's website (same guy who set up the Lippmann forum at holographyforum.org) http://www.designerinlight.com/lippmann/ It doesn't appear to be linked to at his website actually, so it's kind of a "backdoor" thing. Most articles aren't in English unfortunately.
His website, also has lots of chemistry formulas. I'm just posting this stuff in hopes of consolidating all sources to this thread.
Formalin is hard to get in the US, unless you are an undertaker. It has been labeled as a carcinogen. You can substitute glutaraldehyd, succinaldehyd or glyoxal. Some of these are available from the Formulary.
Hey, thanks for everybody's input. Especially the holo links.
What factors go into successful developing, that is, how can you avoid shrinkage? (no jokes necessary.... )
Is it temperature dependent, agitation, chemical, etc.? Lemme guess, all of the above! I wonder what the success rate is.
So here's a question... if you used mercury, would the shrinkage problem be minimized? Why must one use mercury? I guess it's because the mirror has to actually be in contact with the emulsion? So just sandwiching a mirror wouldn't work I suppose.
For what it's worth, making emulsions is way out of my league at the moment; I'll stick with the limitations of the available plates.
Lastly, could someone explain this sentence.... "The Slavich [PFG-03c] emulsion requires pre-development hardening in a formaldehyde solution." Is this the fogging that R Shaffer was referring to??
BTW: Lippmann plates can be projected, which to me seems like one of the most practical ways to display. It requires an aphengescope type projector (basically an opaque projector as far as I can tell). Here is a book link that describes it.... http://books.google.com/books?id=pqk...escope&f=false
I'm certainly far from clear on the physics involved, but
Your recording in the film emulsion an interference pattern that occurs when light is reflected, the wave going out messes up the wave coming in. And if you have an emulsion with a fine enough grain, the interference pattern can be recorded. When you reverse the light reflection in the exposed & developed plate, it alters the light wave lengths to those you recorded and you see color . The paper you sent me has a much better description of what is happening.
The mercury acts as a mirror and so does the air-film with black space. Since the object, if you will, that we are recording is millionths of a millimeter, the gap between the mirror & emulsion would need to be incredibly small. The mercury mirror does move the location in the emulsion where the pattern is recorded further in. I don't know if this makes it easier to record or less sensitive to shrinkage & expansion.
The fogging I was referring to is due to the very small particle size in the emulsion. It can fog with-out light, but I don't know if it is a chemical fogging or something else. It can be cured.
Originally Posted by Photo Engineer
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