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Photo Engineer
06-03-2005, 04:53 PM
Most of the emulsion formulas from before 1940 are very primitive and involve some rather tricky steps. Recent ones published in patents are quite different and just as difficult but in a different fashion. For a good example of a modern emulsion see US Patent 6,524,782. This is a modern t-grain make.

Even if the average person could make a good emulsion, coating it well for in camera or paper printing use would be difficult. Finding the right film support or paper support would also be difficult, as you must have the right substrate to coat on or you get poor adhesion or desensitization. Anyone out there know how to get plain baryta paper with no emulsion on it?

Another sensitzing dye sometimes used in the 40s and still available is Erythrosin, or tetra iodo eosin. This was reported in early work by Eastman Kodak and other companies as a good ortho sensitizing dye. It is still available and is not overly expensive when you consider the amount needed to sensitize an emulsion.

PE

avandesande
06-03-2005, 04:55 PM
http://silvergrain.org/Photo-Tech/literature.html

http://www.amazon.com/exec/obidos/ASIN/0195072405/qid%3D1117835532/sr%3D11-1/ref%3Dsr%5F11%5F1/104-2353793-1649551

avandesande
06-03-2005, 04:57 PM
If you find something you want look it up at the sigma/aldrich site. It will give you a rough idea on pricing

http://www.sigmaaldrich.com/catalog/search/AdvancedSearchPage

avandesande
06-03-2005, 05:04 PM
where would we be without the web???

http://www.grafixplastics.com/acetate_film.asp

http://www.reuels.com/reuels/page440.html

Jorge
06-03-2005, 05:07 PM
Now that is more like it, the book can be had used for a great discount....Thanks Aaron!

donbga
06-03-2005, 05:10 PM
Anyone out there know how to get plain baryta paper with no emulsion on it?


PE

According to Christian Nze, Bergger sells plain baryta paper with no emulsion.

Good luck,

Don Bryant

avandesande
06-03-2005, 05:18 PM
Hurry up and order one. I couldn't help myself.

Now that is more like it, the book can be had used for a great discount....Thanks Aaron!

Photo Engineer
06-03-2005, 05:47 PM
where would we be without the web???

http://www.grafixplastics.com/acetate_film.asp

http://www.reuels.com/reuels/page440.html

Thanks for the quick reply, however I should have noted that the transparent support for coating must be subbed or the gelatin will not spread or adhere. Only a few companies do this. Jim Browning has published one source for that type of support, but it is only available in large rolls.

The same is true for RC paper support. It must have a titanox layer, resin and then a subbing layer for adhesion.

The baryta from Bergger will be usable, if available. I hope I can get it in less than master rolls.

PE

avandesande
06-03-2005, 06:57 PM
What does 'subbed' mean (as far as acetate film is concerned)?

avandesande
06-03-2005, 07:03 PM
Similar to this....??

The polymers per se disclosed in U.S. Pat. No. 3,501,301 are particularly preferred for operation in accordance with this invention. The most preferred polymers for use as a subbing layer in accordance with this invention are a terpolymer of vinylidene chloride, acrylonitrile, and acrylic acid and a copolymer of vinylidene chloride and acrylonitrile.

It is a requirement in accordance with this invention in order to solve the problem of blisters, outlined above, that the subbing layer be applied from an organic solvent solution. Any suitable solvent for applying the subbing layer to the substrate may be employed such as, for example, dichloromethane, ethyl acetate, methyl ethyl ketone, trichloromethane, carbon tetrachloride, ethylene chloride, trichloroethane, toluene, xylene, cyclohexanone, 2-nitropropane, and the like. Dialkyl ketones, for example, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, methyl isopropyl ketone and the like are preferred. Methyl ethyl ketone is most preferred. Alcohols such as methanol, ethanol, propanol, butanol, isopropanol, and the like may be used in mixture with the above-mentioned solvents. In applying the subbing layer to the substrate, the ratio of polymer to solvent is not critical; however, the polymer to solvent ratio employed is preferably from about 0.1 to about 10 percent by weight. The subbing is then dried to remove the solvent and the antistat layer is next applied to the subbed film support.

Photo Engineer
06-03-2005, 07:18 PM
Basically, film support and resin support used in RC papers repel water and therefore they repel gelatin in water. A special material that adheres to film support or the resin and is porous enough to allow gelatin to adhere to it is ideal as a subbing.

If a plain polymer is used, it might work, but then as soon as you dipped the film into water for processing, the polymer would dissolve and allow your emulsion layer to float off in a thin sheet. Therefore, not any polymer will do. It must be hardenable or must somehow set up permanently while still allowing the emulsion layer to adhere.

At the same time, it cannot be too acidic or basic or oxidative or reductive, otherwise you mess with the emulsion.

See how easy it is?

PE

Photo Engineer
06-04-2005, 12:36 PM
Can someone give me more information on Baryta support from Bergger? A contact or something? Someone who has actually purchased some?

Thanks.

PE

glbeas
06-29-2005, 06:15 PM
I found an interesting item in an Ebay ad, Kodak roller transport cleanup film 4955. It's basically film base with a layer of gelatin coated on both sides. Someone needs to try this with Liquid emulsion and see what happens. It would make it possible to shoot hand coated film in standard film holders.

Jorge
06-29-2005, 07:20 PM
I found an interesting item in an Ebay ad, Kodak roller transport cleanup film 4955. It's basically film base with a layer of gelatin coated on both sides. Someone needs to try this with Liquid emulsion and see what happens. It would make it possible to shoot hand coated film in standard film holders.
I think this would make a great support for Carbon tissue....where is the auction?

glbeas
06-29-2005, 09:17 PM
Heres the link :

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7526227865&ssPageName=ADME:B:WN:US:1

I think Kodak still supplies it. You might contact the buyer, I'll bet they were after the Tmax and care nothing about the transport cleaner and may sell it to you.

Jorge
06-29-2005, 09:27 PM
Heres the link :

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7526227865&ssPageName=ADME:B:WN:US:1

I think Kodak still supplies it. You might contact the buyer, I'll bet they were after the Tmax and care nothing about the transport cleaner and may sell it to you.
Thanks Gary, I might just do that.. :)

Ryuji
08-26-2005, 03:00 AM
The manufacturers usually apply corona discharge treatment to the surface of polyester film and sub the surface with styrene butadiene latex copolymer or something similar. But they probably have more efficient methods by now. (Years ago they used one or more extra steps of subbing before gelatin layer) Once the polyester is thus subbed, the surface is ready to accept aqueous gelatin coating. Cellulose triacetate film is a lot easier in this regard. (That's why a lot of films made by low-tech manufacturers use triacetate base.)

In terms of the polymer technology that went into the film base, APS films are the top. They specifically designed a kind of polyester (annealed poly(ethylene naphthalate)) which is just as durable as PET but doesn't curl. I think only APS-participating manufacturers have this technology. (The process to make this type of film base is a lot more involved than plain PET film base.)



Basically, film support and resin support used in RC papers repel water and therefore they repel gelatin in water. A special material that adheres to film support or the resin and is porous enough to allow gelatin to adhere to it is ideal as a subbing.

If a plain polymer is used, it might work, but then as soon as you dipped the film into water for processing, the polymer would dissolve and allow your emulsion layer to float off in a thin sheet. Therefore, not any polymer will do. It must be hardenable or must somehow set up permanently while still allowing the emulsion layer to adhere.

At the same time, it cannot be too acidic or basic or oxidative or reductive, otherwise you mess with the emulsion.

See how easy it is?

PE

Ryuji
08-26-2005, 03:07 AM
I have Tani's book, from which I learned A LOT, but I have to warn you. Tani's main interest is the mechanism by which light exposure is registered in silver halide crystals. His book gives a very concise general account of how emulsion is made, but the setup is very schematized and the book isn't aimed to describe how to make emulsions. This is a very scientific book. If you are an emulsion maker with good background in material science an d electrochemistry, you'll learn a lot from this book, but otherwise this is simply a wrong book to consult.



http://silvergrain.org/Photo-Tech/literature.html

http://www.amazon.com/exec/obidos/ASIN/0195072405/qid%3D1117835532/sr%3D11-1/ref%3Dsr%5F11%5F1/104-2353793-1649551

Ryuji
08-26-2005, 03:11 AM
The first one is a good dye to use, but unless you use a supersensitizer together, the speed won't be very good.



If you had to you could try these for starters :-)

1, 1'-diethylcarbocyanine chloride (was marketed as sensitol red in the 1930's)

or 2-p-dimethylaminostyryl-pyridine methiodide

Both found in 1930's publication and with referance to Eastman Kodak Research laboratories.

Ryuji
08-26-2005, 03:20 AM
Those old German formulae are obsolete and not useful today, because gelatin they used is very different from gelatin available today. One large factor in high quality emulsions Germans could made in 1930s is because they had a wide range of gelatins available, and they blended depending on the application at hand. Today, quality of gelatin is managed in very different ways. Impurities present in 1930s gelatins are largely removed. It was the impurities that played important role in old emulsion making practice. Today, emulsion chemists introduce those "impurities" deliberately in the reacting vessel instead of relying on empirical gelatin blending.

I have much of relevant BIOS and FIAT reports but they are only good for historical studies...

Speaking of historical literature, there are very comprehensive books on industrial chemistry of photography in 1920s, written by a famous AGFA chemist who later came to work for ANSCO. Unfortunately all of his books are written in German language. (I have a copy of the most interesting one.)


Actually as someone who patented a photographic process / emulsion there is not much you can really do in practice as very small differances would get around it.

For easons of commercial secrecy companies don't publish their formulae.

The best (and only) source of good published emulsion formulae was made available after WW11 by the Allies when they translated all the Agfa Gevaert formulae. The books are quite difficult to get hold of, I employed a consultant in the 70's who happened to be related to the Lumiere family, (of Autochrome fame) and had acquired their copies.

These books went into great detail of all the manufacturing and coating techniques, I copied what I needed at the time.

Ian