Re: Speed Point in PT/PD printing?

Clay,

Palladium, platinum and kallitype are all based on the light
sensitive qualities of ferric oxalate. On exposure to ultraviolet
light, ferric iron is reduced to ferrous iron, Fe (2+). However, to
make a permanent print, ferrous iron must be further reacted with
something else, the something else being palladium, platinum or
silver. There is no question but that the major variable is ferric
oxalate, but the metal with which ferrous iron is reacted also plays
an important role in final density with a given time of exposure.

I used two different light sources in my work. With one source
Kallitype and palladium curves are almost identical, but kallitype is
over 1/2 stop faster than palladium. And a combination of platinum is
even slower than pure palladium. However, with another source that
peaks at a different wavelength, a mixture of of pt/pd is faster.
This suggests to me that the metal itself is a very significant
variable.

Sandy

>On Sunday, November 9, 2003, at 01:37 PM, Eric Neilsen wrote:
>
>>Sandy, Have you looked at Mike Wares info on PT/PD printing in relation to
>>moles of PT and/or PD produced at various wave lengths? You might be able to
>>establish a speed point for a PT/PD mixture but with the variations
>>possible, WHY/
>
>It seems to me that the key variable is most likely the ferric
>oxalate - i.e. the light sensitive compound rather than the metal
>itself that would be the critical factor here. Don't you observe
>pretty similar print curve shapes with Kallitype as you do with
>palladium, Sandy?
>
>At any rate, I think that any results Sandy may achieve will be the
>usual 'adjust for your own working conditions' sort of observations,
>and at the very least would give a nice sense of the relative speed
>differences in light sources for this process.
>
>Clay
Received on Sun Nov 9 15:25:30 2003