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 )
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.
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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.
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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.
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The emulsions in this book are all listed as ASA 1, though, just like liquid light.
Originally Posted by Robert Kennedy
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.
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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.
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
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.
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.