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  1. #1

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    Mixing Foma liquid emulsion

    I've tried searching the forum and google for an answer, but haven't found it. So I try to ask here.

    How much water should I add to Foma Liquid emulsion?
    Do I need to heat the original container first or do I just use a plastic spoon or something to take out only the emulsion I need?
    How much do I need to coat a 8x10" paper with two layers?

    How to apply the emulsion I have found good information about, but not about how to mix.

    Guess I at least have to spend the first kilogram of emulsion just for practice, but it would be okay to start with the right mix and work from there. I have ordered the book Gandolfi recommended, but it won't arrive until a few weeks.

  2. #2
    Photo Engineer's Avatar
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    If you can, remove just the amount you need and melt it at about 100 - 110 F (or 35 - 40 C).

    You should add a surfactant and hardening agent for best results. However, you should run a test first to see if these are needed. As for diluting, some emulsions need it and some do not. The company should supply specifications, but if they do not, you may need to use some trial and error to find out what to use.

    Usually, the spread or "lay down" of a silver halide emulsion of this sort is about 5 - 15 ml per square ft. That would be about 45 - 135 ml per square meter at a rough estimate. Again, experimentation is necessary if the company does not give any data.

    PE

  3. #3
    gandolfi's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    If you can, remove just the amount you need and melt it at about 100 - 110 F (or 35 - 40 C).

    You should add a surfactant and hardening agent for best results. However, you should run a test first to see if these are needed. As for diluting, some emulsions need it and some do not. The company should supply specifications, but if they do not, you may need to use some trial and error to find out what to use.

    Usually, the spread or "lay down" of a silver halide emulsion of this sort is about 5 - 15 ml per square ft. That would be about 45 - 135 ml per square meter at a rough estimate. Again, experimentation is necessary if the company does not give any data.

    PE
    10+ years of experience tells me this:

    Don't dilute!!
    There will be a small bottle with hardener in the package - I never use it!

    Just apply an even layer - let it dry and do it again. IF the results are grey/spotted, you have used too little emulsion - if the image looks highly contrasty and slightly yellow - then you have used too much.

  4. #4

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    Thanks. The last text says "melt the emulsion in a water bath", but not spesific about dilution. Guess I just start with a little water to see how liquid the emulsion changes when heated to 40 degrees.

    My plan is to cut a 8x10" in four pieces and coat them. Then I have one or two papers for testtrip, one for normal exposure and one with dodge/burn. If that works well I can coat several 8x10" and start printing. Bought some really heavy weight, textured cotton paper, so it will be interesting.

  5. #5
    gandolfi's Avatar
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    Quote Originally Posted by Grainy View Post
    Thanks. The last text says "melt the emulsion in a water bath", but not spesific about dilution. Guess I just start with a little water to see how liquid the emulsion changes when heated to 40 degrees.

    My plan is to cut a 8x10" in four pieces and coat them. Then I have one or two papers for testtrip, one for normal exposure and one with dodge/burn. If that works well I can coat several 8x10" and start printing. Bought some really heavy weight, textured cotton paper, so it will be interesting.
    as said: NO dilution.

    and PE says you have to melt in 35-40degrees hot water. In my experience it is too low. I always melt at about 45-50degrees.(not higher!)(runnng water!). If you can the emulsion to melt at 35-40 degrees, you'll have trouble keeping it liquid..

    (take a tray and fill som ehot water in it. In there you put a piece of cloth. A plastic container (used boxes for "Ferrero Rocher" works great!!) is put ober the cloth (the cloth makes it stable). Take the container with the melted emulsion in a can with hot water and place that in the tray too.. this way you have hot inviroment around the emulsion all the time while you coat..)

  6. #6

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    Ah, I diluted the first "batch" with water. But I didn't make more than a maybe 50ml and 4 10x15cm sheets. I will throw them away and try again tomorrow.

    Thanks a lot for the input.

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    First problem I discovered with the paper was that it curled upwards in the middle after i started applying the emulsion. And I need to buy a new thermometer, it stops at 40 degrees.

  8. #8
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    If this emulsion is thick at 40 deg C, then it indicates a very high percentage of gelatin. Normally, gelatin is coated between 5% and 10%. Any higher leads to difficulty melting as noted above. I'm afraid I cannot give much advice in this case as I try to stay at what I am comfortable with in terms of concentrations.

    If the paper curls, you may be putting down too much emulsion at one time, you may have humid darkroom conditions or you may be using a cold press or soft textured or low weight paper. I use 100# paper, or higher, and I do not use cold pressed.

    I wish you the best of luck.

    PE

  9. #9

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    I used some high quality 425g/m2 watercolour paper with quite heavy texture. Guess it's cold pressed, but I do not fully understand what the text "Not (cold pressed) grain fin" means.

    It was easier to coat it when I cut 15x20cm sheets instead of 10x15cm, but they still curled in the middle. They're drying now, so I will print tomorrow or monday.

    After I have gotten used to coating and printing on paper I plan to coat different types of rock and wood with emulsion. What can I coat the emulsion with to make the picture more or less weather resistant? I looked at my local art shop and they sold this http://www.hahnemuehle.com/prod/en/2...ive-spray.html and this http://ghiant.com/i/varnish2o.jpg

  10. #10
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    Grainy,

    Almost all watercolor paper will curl will it gets wet. You can actually use that to your advantage. I prefer paper that has a good, strong curl. If you're seeing one long upward cup/curl down the length of the paper, you're coating correctly to the grain. If you coated the other direction (i.e., against the grain), you'd be seeing 'washboarding' -- guaranteed to produce uneven emulsion. But, if you coat with the grain, and then immediately stick something round under the curl when the paper is wet and leave it there for the whole drying time, you will never get any emulsion pooling that can leave you with too-thick spots. I use cut lengths of the pool toy things -- plastic noodles (??) I think they're called -- made of plastic foam.

    d
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

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