From: Monnoyer Philippe (monnoyer@imec.be)
Date: 10/29/03-05:40:18 AM Z
Sandy,
I never printed kallitypes. However, even if the toning would (and we now it's not true apparently, see Glafkides in Christian's post) make pure platinum particles, I would expect it to be different in color/tone.
I expect that because in all our processes with noble metals like Gold, Platinum, Palladium, and even silver, the print color results from the "plasmon resonance" of these particles. When light comes on the particles, their electron "cloud" starts to vibrate and this gives the particular color. What influences the color is the SIZE of the particles and the METAL they are made of. For example, the finest gold particles are red (Casius purple in red glass in old cathedrals). If they agglomerate they turn blue. If they have shapes other then spherical, they can even have green colors (see for example the book of Mike Ware on Early Photographs Deterioration).
And what changes the size and shape of these particles ? THE PROCESS that made them.
That's why I would doubt the platinum particles would be very identical in the toned kallitype case or in the straight platinum print. A good way to analyze which print is which is to have a reflection spectrography (reflection intensity vs. wavelenght). If you have a difference in particle shape/composition/size, the prints will have a different tone, meaning their own signature in reflection spectrography.
If the difference is big enough (I think it would be so), you can use your reflection densitometer. This will give you 3 data points of the so-called reflection spectrograph. That way you might already be able to sort out toned kallitypes and platinotypes.
And this is only one way to do it.
Have fun and if you try it, give us feedback,
Philippe
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