[alt-photo] Re: tintype

[Vedos]

How will it be known if the cyanide did the job then, until we are long dead? Actually, with cyanide we can easily be soon dead! We do wpc with students, but never think of using potassium cyanide in these conditions!

The fixing has been done both with cyanide and hypo from the beginning... here's what John Towler recommends in his "Silver Sunbeam", from 1864, chapter 17:

"Cyanide of potassium is not only a solvent of the silver salts above mentioned, but also a reducing agent; it thus produces in the ambrotype and the melainotype a whiteness in the silver film which can not be effected with hyposulphite of silver. For this reason it is regarded by many photographers as the fixing agent peculiarly adapted for collodion positives by reflected light; whereas in the negative, where the whiteness of the silver film is of little or no consequence, hyposulphite of soda is regarded as the proper fixer. Many photographers disregard these refined distinctions, and use, in consequence of the superior solvent properties of cyanide of potassium, this substance as a fixing agent indifferently for negatives and positives. But because cyanide of potassium dissolves the silver salts so easily, it has to be used in a dilute condition, and to be watched very closely, otherwise it will dissolve at the same time the fine parts of the image."

Best regards,
Jalo


-- If you only look at what is, you might never attain what could be --

V E D O S
Alternative Photographic Processes
Satakunta University of Applied Sciences
vedos at samk.fi
http://vedos.samk.fi
http://www.samk.fi
________________________________________
From: alt-photo-process-list-bounces at lists.altphotolist.org [alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of etienne garbaux [photographeur at nerdshack.com]
Sent: Saturday, November 06, 2010 5:55 PM
To: The alternative photographic processes mailing list
Subject: [alt-photo] Re: tintype

Cor wrote:

>I am not buying this, all the stuff I have read have never mentioned
>this (I would be gladly corrected by you if you have scientific
>references), and my own experience tells me that development is
>extremly fast, an overexposed plate pops up in just 1-2 seconds
>after covered by developper..granted it might be surface development
>only, do not know that.
>
>Also fixing with fresh standard rapid fix shows that the completly
>unexposed parts are visually fixed in 20-30 seconds, another in 30
>seconds are added for safety, leaving a very clear collodion layer
>in the (unexposed)  deep shadows.

If you search the conservation literature, you will find a number of
references questioning the archivality of thiosulfate-fixed collodion
images.  I may have several of the papers around here somewhere, but
if I wanted them I'd do a literature search rather than trying to
find them.  And yes, the development is all on the surface (several
conservation articles present electron microscope sections of
collodion photos that show this very clearly), because by the time
development occurs the developer cannot penetrate the collodion very
well or very far.  For this same reason, neither can the fixer -- and
therein lies the problem.

Feel free to use thiosulfate, and I understand that quite a few
current practitioners do.  But as I said before, it won't be known if
it really did the job until we are long dead.  (Perhaps not such a
bad thing, actually -- IMO, relatively few photographs deserve to
survive for centuries.)  The collodion negatives, prints, ambrotypes,
and tintypes I made starting in the late '60s are all doing fine so
far (all fixed in KCN).

Best regards,

etienne




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