From: Sandy King (sanking@clemson.edu)
Date: 01/25/02-02:21:26 PM Z
Sorry, my last message may have been confusing as to who said what,
so for clarification, Sandy King wrote:
>
>And if you tone the kallitype with platinum it will become even more
>difficult to tell the difference between the two! In fact, I
>understand that a very expensive testing procedure would be needed
>to distinguish between a full-bloom platinum and a platinum-toned
>kallitype.
>
>I platinum tone all of my kallitypes, not to fool anybody but
>because I think it greatly adds to their permanence. What I do is
>develop the kallitype in a 20% sodium citrate developer, which gives
>a warm brown image, then tone with the formula Dick gave yesterday
>(5 g of citric acid per liter of water, plus 5ml of platinum #3
>solution). This is done after clearing but before fixing. Toning is
>usually a subtle process but with this developer/toner combination
>the result is quite dramatic as the brown image rapidly turns to a
>neutral black on contact with the toner. Less rapidly of course as
>the toner depletes.
>
>As for image permanence, which has always been an issue with the
>kallitype, one could make a good case that a well-processed
>kallitype, platinum toned, is as permanent, if not more so, than any
>other type of silver image. The keys to permanence would seem to be,
>1) complete removal via clearing of unused iron, 2) proper fixing of
>the image to remove the unused silver, and 3) complete removal of
>the hypo via adequate washing, or its conversion through the use of
>a hypo eliminator which allows a shorter final wash.
>
>Sandy King
in response to Peter Marshall, as follows.
>
>>
>>I've made prints from the same neg and the only way I could tell
>>which was Pt/Pd and which Kallitype was by looking on the writing
>>on the back. I
>>was using a developing out method with both processes, and there were no
>>significant differences in tonality/tonal range.
>>
>>We have speculated in the past that some 'platinum' prints in collections
>>may actually be kallitypes. There were several formulae published around
>>1900 which claimed to produce kallitypes which looked identical to
>>platinum.
>>
>>Peter Marshall
>>Photography Guide at About http://photography.about.com/
>>email: photography.guide@about.com
>>_________________________________________________________________
>>My London Diary http://mylondondiary.co.uk/
>>London's Industrial Heritage: http://petermarshallphotos.co.uk/
>>The Buildings of London etc: http://londonphotographs.co.uk/
>>and elsewhere......
>
>
>--
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