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  1. #1

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    An old femulsion formula I've found

    This formula is from a book called "Simple photographic experiments". I don't have the book, just the photocopy of the relevent pages, so I don't know who wrote it, but it refers to the 1906 issue of 'Practical Photographer', so I suppose it is well before WW1 and British.

    I have translated the formula from imperial to metric and simplified the instruction slightly, but otherwise this is as published:

    Solution A:

    Potassium Bromide 5g
    Potassium Iodide 0.25g
    Gelatine 15g
    Water 120ml

    Solution B:

    Silver Nitrate 7.5g
    Distilled Water 45ml

    Ammonia .880

    Method:

    Mix solution A using boiling water and stir until dissolved.

    In a separate beaker dissolved the silver nitrate in the cold distilled water. Now add .880 ammonia drop by drop. It will turn muddy brown. Continue adding and shaking until the solution becomes clear again.

    Place both beakers in a water bath until they both achieve 38 degrees C.

    In red light:

    Slowly pour B into A stirring vigorously with a glass rod.

    Place the mixture in a water bath of nearly boiling water for 2 hours.

    Pour into a clean cold porcelain dish and leave to cool to room temperature in the dark, at least 6 hours.

    Now shred to noodles and soak in water for one hour, stirring occasionally. Carefully pour off the water and repeat.

    Return to a beaker and place back into a water bath of nearly boiling water. When remelted, pour into a brown or opaque glass bottle and add 8ml of water containing 0.065g of Chrome alum*

    After shaking, the emulsion is ready to coat the plates.

    Final volume should be about 240 ml


    *I think 1 gram of Chrome Alum in 100ml water would be about right, then add 6ml?

    I'm curious as to what you all think before I try it. Obviously it will be unsensitized and very slow, but it doesn't have much silver nitrate in it, which appeals to me due to the cost! Compared with the other 'real formula' on the thread lower down this forum, it seems very high on gelatine and very low on silver. Is it still classed as a SRAD emulsion, with the ammonia added to the silver nitrate rather than the emulsion?
    Is the ripening temperature a bit excessive? (It did specify nearly boiling). Will it work with an inactive gelatine?

    So many questions, I suppose the best thing is to try it - but will I be wasting my time?

    Cheers,

    Steve

  2. #2
    ben-s's Avatar
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    Interesting stuff.
    I suspect that the addition of the Chrome Alum would render the emulsion uncoatable pretty quickly.
    Maybe divide the batch in half and add the Chrome Alum immediately before coating?
    I guess it's a small enough batch to make experimentally, without worrying too much about the cost.
    Based on a quite I got a while back, I would estimate that this would cost around £10 - £15

    No doubt PE can dive in and either confirm or debunk what I have said
    Lens caps and cable releases can become invisible at will. :D

  3. #3

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    Well, being a complete novice, I'm not totally sure what the chrome alum would do to the gelatine...

    I've got all the chemicals and equipment and I'm ready to give it a go, but I did think that a sensible first step, since gelatine is fairly cheap, might be to clean my glass and coat them just with gelatine. This gives me the chance to practice with melting, coating, drying etc. without wasting the all precious Silver Nitrate. I intend to have a play tommorrow.

    Steve

  4. #4
    ben-s's Avatar
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    AFAIK, Chrome alum is a hardener.
    It will help stop the gelatin melting in the process chemistry.
    EDIT:as confirmed here, Chrome alum is a hardener, and is the correct stuff to use if you're coating on glass /EDIT

    In PE's youtube demo, he uses a dyed gelatin to test the coating properties.
    You might try that - a few drops of food colouring in the plain gelatin would help you to see where it's going.
    Let us know how you get on.
    Lens caps and cable releases can become invisible at will. :D

  5. #5

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    hello jelo

    Quote Originally Posted by ben-s View Post
    AFAIK, Chrome alum is a hardener.
    It will help stop the gelatin melting in the process chemistry.
    EDIT:as confirmed here, Chrome alum is a hardener, and is the correct stuff to use if you're coating on glass /EDIT

    In PE's youtube demo, he uses a dyed gelatin to test the coating properties.
    You might try that - a few drops of food colouring in the plain gelatin would help you to see where it's going.
    Let us know how you get on.
    why not spend $.29 for a pack of sugar free(sugar in regular gelatine deserts is the largest by wieght and volume constituent) fruit gelatine desert and add the alum and try it-- the color is built in

    disclaimer: DON'T STORE ANY LEFT OVER MIX IN REFRIGERATOR-IT IS A POISON AND THE ACCIDENTAL INGESTION -CAUSE IT LOOKS AND SMELLS LIKE JELO-COULD BE FATAL TO A CHILD OR SMALL ADULT-DISCARD LEFT OVER MIX IMMEDIATLY AND TAKE THE 29 CENT LOSS

    i'm being introduced to the vagaries of gelatine on glass myself, and find that for the mechanics of the coating such an approach is very cost effective

    VAYA CON DIOS

  6. #6
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    This emulsion is an SRAD (Single Run Ammonia Digest) emulsion similar to the one I posted earlier in this forum. It is a good formula which will work reasonably well.

    It will be slightly slower due to the fact that the gelatin level is higher from what I see. As gelatin goes up, grain size goes down and therefore speed decreases.

    The ammonia is 28%. DO NOT USE HOUSEHOLD AMMONIA. It is too dilute and will result in a poor emulsion. You must get the 28% from a chemical supply house. Also, be aware of the extreme fumes produced by this method. You will need good ventilation.

    Try it, it will work.

    Oh, chrome alum is indeed a hardener, and if you have not washed out all of the ammonia it will harden rather quickly.

    PE

  7. #7

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    gelatine issues

    Quote Originally Posted by Photo Engineer View Post
    This emulsion is an SRAD (Single Run Ammonia Digest) emulsion similar to the one I posted earlier in this forum. It is a good formula which will work reasonably well.

    It will be slightly slower due to the fact that the gelatin level is higher from what I see. As gelatin goes up, grain size goes down and therefore speed decreases.

    The ammonia is 28%. DO NOT USE HOUSEHOLD AMMONIA. It is too dilute and will result in a poor emulsion. You must get the 28% from a chemical supply house. Also, be aware of the extreme fumes produced by this method. You will need good ventilation.

    Try it, it will work.

    Oh, chrome alum is indeed a hardener, and if you have not washed out all of the ammonia it will harden rather quickly.

    PE
    pe i dont mean to dvert this thread and appologise if i doso

    i can get 250mg of 250 bloom 'photo gelatine "actvated"(?) for $50

    it is presalted afaik for a agno salt emulsion-included is a book of instructions and methods he uses-very comprehensive-the combination of the book and the gelatine may be worth the price?-i am moving towards the salt emulsion anyway-he gives emulsion speeds from 1/2-5 iso in different applications and coatings

    he also adds iodides and bromides for more speed and other reasons

    if i sh ould address this elswhere please tell me

    vaya con dios

  8. #8
    Photo Engineer's Avatar
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    IDK what this is and I cannot comment on any of its characteristics or usefulness.

    Good luck.

    PE

  9. #9

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    Thanks for the feedback, guys.

    I will be making this emulsion this week. I've took the first few steps by aquiring all the chemicals and equipment I need. Tonight I will be preparing the glass slides (cleaning) and playing with some gelatine and alum.

    z-man, thanks for the advice and warning about poisoning the family, but I have solved the problem of child interference completely - by not having any!

    I have decided to use the garage (completely seperate from the house) as the emulsion manufacturing plant (!) as I can make as much smell as I like...

    My main problem right now is the ammonia. I can not get .880 or anything anywhere near. Things have been getting very hard just lately due to the 'security situation'. I work from home and in my job use lens cleaning solutions containing alcohol and various solvents. My own company can not now send these legally to me, their own employee, by post. Most couriers seems to have imposed their own rules about not carrying liqued chemicals and refuse to carry anything.

    We have a couple of excellent suppliers in the UK for photographic chemicals, Silverprint and Retrophotographic. Neither of them list any liqued chemicals anymore or many of the dangerous ones, presumably for the same reasons. Certainly no .880 ammonia.

    We are currently in the middle of a big security alert in the UK after the plot by several doctors (DOCTORS?!!) to bomb airports - so this is not a good time to be approaching chemical suppliers for restricted chemicals :o

    I have a plan, though...

    After rummaging around in the loft I found two things that might save my bacon. Firstly a big box of chemical apparatus. Flasks, glass tubes, bungs, burrettes, etc and secondly a 100yr old book called 'A laboratory Outline of General Chemistry' by Hale and Smith, 1907. A beautiful manual written in a different era entirely, when people were credited with some common sense and before Terrorists and Health and Safety Officers spoiled everything.

    This tells me how to make ammonia from Ammonium Chloride (which I can buy legally and get posted to me).

    My other idea was to get a gallon of houshold ammonia (I can buy this in the shops, but it is only about 9% strength and I'm not sure what else it might contain) and put it in a flask, heat it and bubble the ammonia gas through some de-mineralised water.

    Anyone know if this would work? And what strenth I could reach? And is their an easy way to test the strength? I have a brewing hydrometer, but would need to make rather a lot to be able to float this in it!

    Anyway - this minor problem won't defeat me - it is actually starting to seem like fun

    Steve

  10. #10
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    Steve;
    Have you tried a chemical supplier like Rose chemicals or Fisher scientific?
    Fisher can supply both apparatus and chemistry, while Rose are a small company who just supply chemicals.

    www.fisher.co.uk
    www.rose-chemicals.co.uk
    AFAIK, Fisher won't deal with individuals, but you should be able to purchase through a company.
    I believe that rose will deal with individuals.

    I wouldn't recommend making your own ammonia unless you have an accurate way of testing concentration.
    Lens caps and cable releases can become invisible at will. :D

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