Re: Bromo-iodide Silver Gelatin Emulsion as an Alternative process.

Oops. I forgot to sign that long tirade...

Any help is appreciated!

Best regards,
Tom Einar

T. E. Andersen wrote:
> Hi all,
> First of all, thank you Michael for the link to the book in question.
> Unfortunately it was not very readable. It seems a lot of formatting as
> well as some tables and figures have gone missing in this archived
> version. Some of the info is still readable, though.
>
> Ryuji,--
> I would very much like any details you can provide. I'm not sure if this
> should be done on the list, but I'm posting this, so that others can
> express their interest (or lack of such). If no one is interested, then
> maybe we should continue off list.
> (I will be off line for several days at a time in the near future, so
> please don't give up on me if I do not respond immediately).
>
>
> This is my situation:
>
> - I'm fairly skilled in basic chemical methodology, and have a
> reasonably complete, but simple laboratory (I run a small microscopy
> lab). As long as things are not too expensive, I am prepared to add to
> my equipment to enable small scale emulsion making and coating.
>
> - I have basic knowledge of how emulsions are made, and their major
> components.
>
> - I have a wish to be able to make glass plates for taking B&H large
> format pictures. This is partly founded in basic curiosity, and partly
> in the wish to be self sufficient if the day comes when film is
> unavailable, or too expensive for me to use (this day seems to approach
> more rapidly than I would have imagined just a year ago). Furthermore, I
> would like to use some slightly odd formats with home-built cameras, and
> using home made glass plates seems like a sensible way to do that.
>
> - I don't care too much about film speed (OK, it would be good with a
> little more than ISO 1.5). If I need speed, I shoot digitally, or with
> colour slide film while it lasts.
>
> - I do care about image gradation. On the other hand, I will probably
> not be enlarging too much, so small imperfections should not present too
> much of a problem.
>
> - I prefer a small grain film, but can easily think of situations where
> that might not be important.
>
> - If it is possible, I do prefer a low-fog film, since I would like to
> attempt reversal processing.
>
> - Any chromatic sensitivity is of interest, in the following order:
> Panchromatic (preferred, but I realize it has severe complications in
> production) > ortho-panchromatic > IR-sensitive (this would be great,
> but no substitute for a visible range film)> orthochromatic > blue
> sensitive.
>
> - I'm in no rush. Before I even try to make an emulsion, I would like to
> know more about what I'm getting into. If I am ready to make my first
> plate a year from now, I will label it success!
>
> - If I do eventually decide to try this, I would prefer to be able to
> make at least 10 11x14 or 20 8x10 plates at one time, preferably more. I
> will probably not be able to make plates more than a few times a year.
> My ideal situation would be to arrive at an acceptable process, and
> within a reasonable time-frame make enough for a years photography (I
> already store film and paper in a freezer).
>
>
> This I don't have:
> - Detailed knowledge of the chemistry of sensitation (I know a fair bit
> about dyes, but not related to emulsions)
>
> - ANY recipes whatsoever (consequently, anything you are willing to
> share from your notebook is very welcome).
>
> - _Practical_ knowledge on how to make the emulsions (i.e. exactly what
> equipment is needed, temperatures and times for nucleation etc etc.)
>
> - Practical knowledge on coating. This is only partly true, since I've
> done a fair bit of cyano, van dyke and a little bit of gum-dichromate. I
> have no idea what it takes to produce an even gelatin film on glass,
> though. I read some holography links that seemed interesting, but I'm
> unsure if those films will be applicable to general photography. Several
> seemed to use a simple "pour on" coating technique. If it is good enough
> for holography, it may be good enough for general imaging as well I
> suppose. I also don't know if I need to order glass larger than my
> end-format, and cut it to size after coating. Possibly coating 20x24, to
> cut it down would save a lot of work?
>
> - You ask what kind of setup I'm willing to use. Well,- I'm not ready to
> answer that. Possibly you can make a recommendation based on the
> information I've given above, or guide me to literature to read up on.
>
> - When you talk about jets, I have no idea whether you are talking about
> some special coating equipment or simply three burettes to supply
> different solutions during emulsion mixing. Quite possibly you are
> talking about something different all together....:-)
>
> Finally; I have no way of getting hold of the papers you mention. Could
> I ask you to send a copy? I'll of course pay for copying/shipping.
>
>
> Ryuji Suzuki wrote:
>
>> I don't have time to answer the question today, but the book in
>> question is pretty bad. I have Wall's book and Baker's second edition,
>> both pretty bad. Indeed, books on emulsions are generally pretty
>> bad. And good books talk about physics and chemistry of emulsion but
>> they won't go into how to make emulsions, as they assume that the
>> readers know it.
>>
>> I can find formulae for plate emulsions from my notebook if you tell
>> me the speed you are looking for, and the kind of setup you are
>> willing to use, etc.
>>
>> It's possible to make a fairly fast emulsion of good gradation and low
>> fog, but it involves a minimum of triple jet setup (one jet each for
>> silver, bromide, iodide), change of temperature after nucleation,
>> sulfur+gold sensitization, etc. And two or three batches of emulsion
>> should be made for blending to increase latitude.
>>
>> On the other hand, formulae that use single jet are easier to follow
>> but they are usually slow, coarse emulsion of nonuniform grain size,
>> with lots of dead (junk) grains that do not contribute to sensitivity
>> or image. This type of emulsion phased out from market in mid
>> 1980s. But you can still make a pretty usable emulsion by this
>> approach.
>>
>> Examples of the former type emulsions appear in relevant patents but
>> those are usually not ready for amateurs to follow (formulae don't
>> include all necessary details). There are some good examples of the
>> latter type emulsions. See Carroll's paper in J. Chem. Education,
>> dated c. 1930. I mentioned this paper a few times in the past, so it
>> should be easy to search. Hill also published another paper in the
>> same journal c. 1960. These are better starter materials than any book
>> I know of.
>>
>> Ryuji
>>
>
>
>
Received on Sat Oct 22 16:24:40 2005