Liquid Emulsions

Discussion in 'Alternative Processes' started by jnanian, Dec 9, 2003.

  1. jnanian

    jnanian Advertiser

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    does anyone have experience using liquid silver emulsions?
    i use liquid light to coat glass plates both for darkroom work as well as in the camera and wanted to find something a little faster for shooting portraits. it is blue sensitive and is sort of fast if i use daylight bulbs or strobes - but it is still pretty slow.

    ever use ag emulsion or another one that might be relative to regular liquid light ?
    ( relative asa of liquid light is 1 or 5 depending on the light source )

    thanks

    john
     
  2. jnanian

    jnanian Advertiser

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    hi -

    i surfed a bit and then contacted rockland colloid about the differences between liquid light and ag ..
    incase anyone was intereseted:

    The speed differential between Liquid Light and Ag-Plus depends on the age of the respective emulsions more than anything else. Having a higher silver content, Ag ages faster than LL, so becomes relatively faster. When emulsions are freshly made, the two are about the same sensitivity.
     
  3. Robert Kennedy

    Robert Kennedy Member

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    First off, if you can find it, get this book.


    Silver Gelatin - A User's Guide to Liquid Photographic Emulsions by Martin Reed and Sarah Jones

    It will even tell you how make a variety of your OWN emulsions. So this is probably something you might like.

    It also cover coating, etc.

    As to the AG Plus.....

    I have heard it is markedly faster, although I have not used it myself yet. The Ag Plus is supposed to be faster. So says Rockland.

    If you do get this stuff, get it from a store if you can!

    I know this may sound odd, but all of the Rockland products get FASTER as they age. So fresh is bad here. Try and find a dusty old bottle in a store with slow inventory. With online suppliers, they may be simply booting the stuff on from Rockland the second they get it. Nice and fresh. You may also want to stock up and store some for 6 months or so.
     
  4. ThomHarrop

    ThomHarrop Member

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    One quick tip I can offer for liquid emulsion is a baby bottle warmer. I bought one and my students and I use it to liquify the emulsion before use. We put a little water in the bottom and put in the Liquid Light or other liquid emulsion and it is ready to use in less than 5 minutes.
     
  5. Nicole

    Nicole Member

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    ...
     
  6. Jeremy

    Jeremy Member

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    The emulsions in this book are all listed as ASA 1, though, just like liquid light.

    Quick additional question: I want do some plates and have everything but the glass--can I get regular ol' window glass from the glass shop? That way I can have them cut it to size.
     
  7. Photo Engineer

    Photo Engineer Subscriber

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    Jeremy;

    No reason why you could not use window glass for plates other than the distortion of the lower quality glass that they use. It must be properly prepared as outlined in the book.

    The emulsions described in that book for the most part don't use any form of sensitization and that is one factor that contributes to their slow speed.

    At present, my emulsions are running at about the same speed as Kentmere graded papers for enlarging (AgBrI) and Azo speed (AgCl). This puts them into the ISO 25 - 1 range. The highest I have achieved is about ISO 100 with a rather difficult ammonia digest emulsion from an ancient text book on emulsion making. I'm working on a simpler formula.

    Contrast ranges from 0 - 2 for the bromoiodide and 1 - 3 for the AgCl when coated on paper support.

    Fog is low and keeping appears good, but then I usually use up the coatings rather quickly. The emulsion seems to keep in the refrigerator for months. Again though, I use it up rather quickly.

    I have posted some pictures in the Alternative section.

    PE
     
  8. jnanian

    jnanian Advertiser

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    hi jeremy

    i use regular window glass - you want to get the thin-est glass possible.

    oh, in the book they sugget mixing developer stock solution with the developer to increase the speed. after speaking with bob at rockland colloid, it was suggested that one doesn't do that ...

    if you haven't been to alternativephotography.com there is a section on dry plating that is really helpful. the person who wrote it ( scott ) is really nice and responds to emails too :smile:

    -john
     
  9. Photo Engineer

    Photo Engineer Subscriber

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    For those who want more information on emulsion making:

    After reading and re-reading "Silver Gelatin" plus a host of textbooks published in the 20s - 40s on emulsion making, I have to add some comments.

    None of these references make clear that there are two types of gelatin. Early gelatins were 'photo grade' but were unoxidized and contained ingredients that could 'sensitize' photographic emulsions. Modern 'photo grade' gelatins are oxidized and have most of these sensitzers refined out of them. These sensitizers must therefore be added at the appropriate time to carry out sensitization otherwise emulsion speed and contrast will be low.

    So, in "Silver Gelatin" or "Wall" or "Baker" (some old texts) the heat treatment after the precipitation can imply sensitization by use of old style gelatin and if used with modern gelatin nothing will happen except some mild ripening due to the heat.

    Ideally, you want to add a sulfur sensitizer to the emulsion after precipitation. If it is Agfa style or 'European' style, the sensitizer was at one time added to the unwashed emulsion, but if it was 'Kodak' style, then the emulsion is washed first before addition of the sensitizer. That sensitizer may be thiourea, allyl thiourea, or sodium thiosulfate. When Kodak revealed this, it revolutionized emulsion making at the time. Later, Agfa's discovery of gold plus sulfur created the second great revolution in emulsion making.

    It has also not been made clear that there are many types of emulsion. The old style emulsions are either ammonia digest or boiled. Neither of these is very nice and neither is used today. The ammonia odor of the one is terrible, and boiling can take up to a day at 90 deg C. Not nice at all.

    All emulsions are classified as to their methodology, and so a single run (silver into salt) with ammonia is called an SRAD emulsion. (Single Run Ammonia Digest)

    There are many such designations in existance today that fill out the emulsion engineers bag of tricks for making the best emulsion for a given product.

    The bottom line is that "Silver Gelatin" can be misleading in the sense that the formulas may be correct or in error but certainly leave out a lot of information sometimes that is needed to make a good high-speed emulsion.

    The Kahn emulsion that I posted a while back is still working just fine for me. I have made it in batches from 120 g to 600 g with great success and have no need to sensitize if I want contact speeds. I have spectrally sensitized it and have created at least 3 contrast grads with good black tones, and BTW, it is almost identical to one of the "Silver Gelatin" emulsions. It just depends on what you want in terms of speed and contrast.

    To make this AgCl emulsion, one must be careful to select "photo grade" gelatin with a bloom index of 175 or higher (250 is nice), and one must use the most pure chemicals you can get. If you get pepper grain (black specks) in your final result, try increasing the gelatin content for starters, or decreasing temperature.

    Contrast control is effected by silver concentration in mg/sq meter or by the addition of dopants and/or doctors to the emulsion before coating. The basic emulsion described in my other post is about grade 2, but by diluting it 1:1 with gelatin at the same concentration as in the emulsion, you will get about 1 grade lower in contrast. How is that for help? That is useful as a starting point for those interested in pursuing it. It now partly answers a question by David Goldfarb in another place here on APUG.

    As I continue to progress, I will give information on things that I know work. As of tonight, I am now one stop FASTER than Ilford MGIV paper (with grade 2 filters) and 2 stops faster than Kentmere grade 2 paper. This was done on-easel with those papers and development in ordinary Dektol for comparison.

    I expect to publish a complete manual in the Fall for making both B&W papers and a medium speed film. Wish me luck, or as George Eastman said "pray for the emulsion".

    Thanks to those who have expressed an interest in this work.

    PE
     
  10. David A. Goldfarb

    David A. Goldfarb Moderator Staff Member

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    Thanks for the update, PE. I'm still refining what I'm doing with albumen, but I picked up some photo grade gelatin from Artcraft, so I can try your silver chloride emulsion when there's a lull in various other projects I've got going.
     
  11. winger

    winger Subscriber

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    With liquid light, is it okay (or even preferred) to melt the whole bottle then pouring out what you need? Or can you melt just 'til you get enough for the amount of paper you're using? And if you open a bottle and use some, for how much longer will what's left be okay? A month or 2? months? years?
     
  12. Photo Engineer

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    David, I have found that all gelatins are not equal when making emulsions. I have 3 different kinds at 3 Bloom Indexes. They are all different. Contact me if you have a problem.

    Things you might see include speed variations, contrast variations, aggregation and pepper grain (black dots on prints).

    PE
     
  13. Photo Engineer

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    See my post on finishing.

    When you heat an emulsion, you tend to restart the sulfur sensitization or restart the ripening process. This can be mitigated by the manufacturer by adding an inhibitor to the emuslion to prevent this. Also, the heat can start bacteria and fungi growth in the gelatin.

    I cannot predict how your liquid light would be affected, but felt it fair to advise you to try to limit heat to nothing more than 40 deg C (68 deg F) and try to limit it to as short a time and as infrequently as possible. This is the only sure way I know to keep an emulsion for a long time.

    There is nothing worse than the smell of a 'furry' emulsion covered with mold and starting to liqufy even in the cold. Unless perhaps it is an emulsion that has been fogged by repeated heat and cold cycles.

    I put mine into wide mouth containers and can then remove what I need by using a large spatula or my hands (with rubber gloves) without heating the whole container. I just cut off chunks and weigh them until I have what I need and only melt what I need.

    PE
     
  14. Kobin

    Kobin Member

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    Fish gelatin for phot emuslsions?

    Has any one tried the liquid fish gelatin sold at:

    http://www.norlandprod.com/fishgel/hipure.html

    to make phot emulsions? The company claims easy, non gelling liquidity of the stuff, solubility in water, and harding upon drying. Might be easiler than messing with the traditional gel type?
     
  15. Photo Engineer

    Photo Engineer Subscriber

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    I know of no case in the photo industry where fish gelatin was used for anything. That does not mean it was not tried, merely that it was not widely known or worked with extensively.

    Cow bone gelatin and pig gelatin are the most common ones, with cow gelatin used far more often than pig gelatin.

    PE
     
  16. JG Motamedi

    JG Motamedi Member

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    Best of luck with the work. I saw the workshop blurb at CFAAHP and it looks great. I also look forward to the manual.
     
  17. Photo Engineer

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    Thanks for the plug.

    I hope to see you there.

    If you prefer 'big sky' country, you might consider the workshop in Montana in June.

    PE
     
  18. Troy Hamon

    Troy Hamon Member

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    PE, just looking through threads about emulsions and noticed this typo...is it supposed to be limited to 40 C (104 F) or 20 C (68 F)? Thanks for your help. Not sure if I'll get to my related project soon, but am interested in trying some of this out...
     
  19. Photo Engineer

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    Troy, thats a typo. It should be 40 deg C (104 F). Gelatin will set up at 20 deg C (68 deg F). Above 40 deg C, the finishing and ripening can speed up and ruin the emulsion. I am distinguishing between these two but some tend to lump them together.

    Thanks for the catch. Sorry.

    PE