[alt-photo] Re: tintype developer formula?
dickburk at ix.netcom.com
Mon Jan 2 18:36:20 GMT 2012
----- Original Message -----
From: "Christina Anderson" <zphoto at montana.net>
To: "The alternative photographic processes mailing list"
<alt-photo-process-list at lists.altphotolist.org>
Sent: Monday, January 02, 2012 6:17 AM
Subject: [alt-photo] Re: tintype developer formula?
I can answer that one: a tintype developer for liquid
emulsion needs to essentially fog the gelatin silver layer
so it is brownish/yellowish and shows up on the black plate.
Thus the addition of fixer to the developer. It still
I figured out a recipe that would use dektol, sodium
sulfate, and ammonium thiocyanate but am not quite sure
whether the proportions have to be within an exact gram
amount or not.
Christina Z. Anderson
On Jan 2, 2012, at 9:09 AM, <C.Breukel at lumc.nl>
<C.Breukel at lumc.nl> wrote:
> Interesting, Christina
> The formula almost looks like a Monobath developer,
> itcontains jut one developing agent as well as a moderate
> amount of hypo (fixer), I guess not sufficient for proper
> fixing, but might have an effect on the silver atoms
> shape..Richard chime in please..;-)..
I'm no expert on this but a couple of things occur to
me: the silver image can be reflective when the grain if
fine enough. This effect can be seen on very fine grain
negatives where a positive image can be seen by reflective
light, especially if the image is not very dense. This does
not come from fogging but rather is a property of the very
Grant Haist wrote a small book on monobath processing, I
don't remember the exact title. It may be available via a
book search. He also discusses monobath processing in his
large book on photographic chemistry. Monobath must not be
confused with reversal processing, they do different things.
Monobath produces conventional negatives, the idea is that
the developer and fixing agent are contained in the same
bath. Because both begin to work as soon as they soak into
the emulsion the developing agent must be one that is
energetic so that the required amount of development takes
place before the fixing agent destroys the latent image and
dissolves the halide. Haist makes a good case that monobath
development works better for some materials than
conventional processing resulting in finer grain and good
tone rendition. The formula must be adjusted for the
particular negative material its to be used with. A properly
compounded monobath does not result in any speed loss
compared to conventional development. However, the bath is
often very alkaline so the emulsion must be hardened or the
bath must contain an organic hardener capable of functioning
in the high pH environment.
Monobaths can also be used for print development, I
think Haist discusses this a bit.
Tintypes, while they are direct positives are _not_ a
reversal process; the image is a conventional negative image
but is viewed by light reflected _by the image_. This is in
contradistinction to a conventional print. In a normal
print, or most alternative processes prints, like Platinum
or carbon, the light is reflected by the support, not the
image. The image serves to modulate the amount of light
transmitted to and reflected from the support. The image on
a tintype must be such as to be reflective. It is likely
that the use of hypo or thiocyanate in tintype developers is
to aid in obtaining the requisite fine grain. Both are fine
grain agents found in conventional fine grain developers,
for example sodium thiocyanate is found in Kodak DK-20.
A problem with some very fine grain negative
developers, which might also be a problem for tintypes, is
the production of dichroic fog: the fine grain agents are
solvents for the silver halide and tend to release a certain
amount of halide which is deposited on the surface of the
film and converted to metallic silver by the developer. This
coating is of extremely fine silver, the kind sometimes
called colloidal silver, and is reflective in one color and
transmits in another color, hence the name "dichroic fog".
This would, of course, veil the shadows of a tintype
reducing its contrast. In some extra-fine-grain developers a
silver sequestering agent is used to insure that the silver
dissolved by the halide solvents remains in solution and is
not deposited on the emulsion.
Fogging is required for _reversal_ development. In
practical reversal development its produced either by adding
a fogging agent to the reversal bath or by flashing with
light. Hypo or thiocyanate, or other halide solvents, are
added to reversal first developers to avoid veiling of
highlights by silver halide crystals which remain in the
emulsion after the first development but are so insensitive
that the original exposure does not make them developable.
If they remain in the emulsion they do become developable
after the fogging step and result in veiling of the
highlights of the reversed image and an effective
substantial loss of speed.
As with monobath processing a reversal process must be
tailored to the particular material being developed.
Los Angeles, CA, USA
dickburk at ix.netcom.com
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