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  1. #61

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    Quote Originally Posted by Hologram View Post
    (...)like dichromated and ferric gelatin. They required a relatively long time of treatment - say, 45 - 60 minutes at 120°C. So this definitely complicates the whole process.
    Speaking of dichromated gelatin, one thing you might try before switching to another developer would be a "DCG-like" approach: put your already exposed/developed plate into a cold water bath for five minutes or so. Then you insert it into an 50% alcohol (isopropanol, ethanol or methanol) solution for two minutes. Then put it into a 100% alcohol bath for another two minutes. When you remove the plate you'd apply a warm air stream (hairdryer etc.) to dry it without causing condensation defects. Let me know if this shifts the reonstructing colors towards longer wavelengths.

  2. #62

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    Quote Originally Posted by Hologram View Post
    Great results, congratulations!

    I don't know whether the two hardeners, formaldehyde and glyoxal, act at similar speed regarding emulsion hardening.
    Maybe glyoxal takes much longer.
    What about baking the plate right after the photographic exposure and prior to liquid processing? I remember having done baking (without adding any specific hardening agent) with a couple of gelatin based materials, like dichromated and ferric gelatin. They required a relatively long time of treatment - say, 45 - 60 minutes at 120°C. So this definitely complicates the whole process.

    Regarding your developer I wasn't aware (anymore) it had such a high KBr concentration. As PE pointed out KBr also acts as a silver solvent. By the way there are colloidal developers that contain but KBr as the silver solvent. Moreover, in my reply to your post at the holography forum I forgot to mention that ammonia is both a silver solvent and a very strong alkali. So increasing/decreasing its amount makes it very tricky in respect to solvent/developing action.
    So switching to another developer may be a better option I guess. There's an alternative to the GP-2 type of developers. I was involved with people from the Russian holography forum to set up a developer which replaces the ammonium thiocyante by sodium thiosulfate. I can't seem to find that link anymore. The whole thing was done with two stock solutions, one containing the thiosulfate only (I believe).
    Thanks

    I was thinking along the same lines with the hardening step, that the glyoxal is not really a 1 to 1 substitute for formalin. But in multiple searches I could not find any info for this application. Seems only us gummies use it for hardening our gelatin sizing. Sounds like a couple of tests are in order.

    I like baking, I don't think my oven goes all the way down to 120deg. But maybe the toaster oven would. Need to get the OK from my wife before I start sticking stuff in the oven though :rolleyes:

    I used the pyro-ammonia since it was (relatively) easy to mix up myself in small quantities, I only have small time windows to play with my little projects. Perhaps it would be better to try and raise the ph of the developer to slow down its activity?

    I have the PF GP-2 developer as well, that I intend to use for another try. I just did not want to mix up a whole liter of developer for the first go as it will be a couple of weeks before I can get back to testing. But I like the idea of a comparable developer that uses regular hypo. I also saw some pyrocatecol developer formulas, I need to see how close they are to my pyro-cat HD, wouldn't that be cool.

    Thanks, this helps.

  3. #63

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    Quote Originally Posted by Hologram View Post
    Speaking of dichromated gelatin, one thing you might try before switching to another developer would be a "DCG-like" approach: put your already exposed/developed plate into a cold water bath for five minutes or so. Then you insert it into an 50% alcohol (isopropanol, ethanol or methanol) solution for two minutes. Then put it into a 100% alcohol bath for another two minutes. When you remove the plate you'd apply a warm air stream (hairdryer etc.) to dry it without causing condensation defects. Let me know if this shifts the reonstructing colors towards longer wavelengths.
    I have a plate I can try this out on and it sounds easy. How cold? Water bath with ice cubes floating in it cold? I was hoping there might be a way to reswell the emulsion.

    And I read somewhere about post processing with a rehalogenating bleach or maybe it was bleaching and then redeveloping to try and restore the emulsion thickness. I need to go back and reread a few things.

  4. #64
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    Robert, this may be what you're referring to....

    "The Lumier developer was frequently recommended and can also be used for modern Lippmann photographs. Development time was 1 to 3 minutes. Most often the image was fixed. However, it was sometimes recommended not to fix the developed image, since that would change the thickness of the emulsion and, change the colour of the image. Many Lippmann photographers used image intensification by a bleaching and redeveloping process, which compensated for the shrinkage introduced by the fixing step." - Bjelkhagen, 'Lippmann photography: its history and recent development', page 3, bottom paragraph.

  5. #65

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    Quote Originally Posted by R Shaffer View Post
    I have a plate I can try this out on and it sounds easy. How cold? Water bath with ice cubes floating in it cold? I was hoping there might be a way to reswell the emulsion.
    I would use all baths at >20°C.

    In order to post-swell the emulsion you might try also a 5% glycerol (sorbitol would be another option) solution.

    Quote Originally Posted by R Shaffer View Post
    And I read somewhere about post processing with a rehalogenating bleach or maybe it was bleaching and then redeveloping to try and restore the emulsion thickness. I need to go back and reread a few things.
    I assume this would imply to develop (or re-develop) the emulsion to increased densities. Then you'd have to use a rehalogenating bleach that does very little damage to the integrity of the Lippmann fringes. Bleaches based on ferric EDTA or copper sulfate, maybe on iodine would come to my mind. The "classic" method implies mercuric chloride but that one surely has to be ruled out.

  6. #66

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    Quote Originally Posted by Hologram View Post
    I would use all baths at >20°C.
    Oopy, that was a typo. I meant to say < (below) 20°C of course.

  7. #67
    holmburgers's Avatar
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    Just so everyone knows, this is still ongoing. No one's given up here!! I'm due to get some experiments going soon and I've been in contact with Darran Green, one of the Lippmann gurus out there. He suggested a slightly modified GP2 hologram developer to use. I think that is what I will go with, as the Lumiere pyrogallol has some deficiencies, apparently.

    basically... BUMP

  8. #68
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    Quote Originally Posted by holmburgers View Post
    Just so everyone knows, this is still ongoing. No one's given up here!! ....
    basically... BUMP
    Thanks for the bump. I'm watching this and really want to see this work. I'm working on a job out of town now, so I don't have any resources to devote to it myself that I can do in a hotel room. But I plan to try it as soon as I can get all of my tasks finished and get back home.
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  9. #69
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    Awesome, I'm glad to hear some others are interested as well. Stay tuned, I guess this isn't for the impatient

  10. #70

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    New Lippman Test Results

    So I have made some changes to my processing of the Lippmann Plate and the results are promising. These were based upon feedback from my initial results from Mr. Darren Green ( thanks )

    I changed the developer to Formulary' GP-2, however the developer is split into a solution A and B. Solution A is all the GP-2 ingredients, except for the Thiocyanate, mixed into 1 liter of stock solution ( GP-A ). The 12g of thiocyanate is then mixed with 200ml H2O for a 6% dilution ( GP-B ). The working developer is 15ml GP-A + 4ml GP-B + 100ml H2O.

    Exposure: 2min @ f/8 bright sun

    Processing:
    9min soak in Glyaxol @ 65deg ( prev. was 6min, did not check end temp )
    3min development @ 65deg ( actually I used drift 63deg start - 66deg end )
    rinse 10min @ 66deg
    30s soak in 2% glycerin + 3 drop LFN @ 66 deg ( 375ml total )

    I was able to get much better color rendition, although the plate is rather dim. I have been told that increasing the GP-B will brighten the plate, but may alter the color.

    I was also told that blue table in the previous image post was solarization. I believe that this is confirmed with the new plate as the white mailbox is turquoise & there is some turquoise in the fence. The 4 min exposure I made of this scene has a significant turquoise cast across entire image.

    The right side of the image was not completely submerged in the glyaxol hardener ( me being too stingy w/ chemistry ), however it seems to show that I am getting good hardening of the emulsion with the glyaxol and it is essential to harden prior to developing.

    So my next test will be shortening the exposure to 1min and 1 1/2min. And increasing the amount of GP-B in the developer.

    Progress
    Attached Thumbnails Attached Thumbnails plate-2min.jpg  
    Last edited by R Shaffer; 05-20-2010 at 12:36 PM. Click to view previous post history.



 

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