> Keith
>
> I am grateful for your constructive reply.
>
> I find that sizing the paper increases perceived contrast and gradation. Use of
> a deionised size appears to avoid problems of adverse reactions between gelatine
> and platinum.
>
Double coating seems to have a similar effect
> I am very chary of reflection densitomiter readings in relation to hand coated
> papers as subjective reactions differ markedly from from those of the
> instrument.
I couldn't agree more and will soon be addressing that issue on list
now that I have sent out all this data. I wish that I could send the
actual 21-step prints with the data to illustrate the point.
> I have a standard procedure where palladium is included in a coating, ( cf the
> work of Mike Ware), which is that after the coating has been dried I place the
> paper in the dark in association with a tray of warm water. This ensures that
> the palladium prints black and not brown. Warmth of tone varies with the degree
> of humidification. or ' humiliation' as students insist.
Last spring after a particularly dry period here in the desert I
finally made the connection between ambient humidity and the grain
problems that I had been experiencing. I began using a room
humidifier in the darkroom which helped a great deal. I also stopped
using potassium chlorate. Instead I began using hydrogen peroxide
which works well to a point. Currently I am using sodium dichromate
added to the potassium oxalate developer in miniscule amounts. This
method allows a wide range of contrast control - much more than I
need - and has the added benefit of allowing many sheets to be coated
in advance since contrast is controlled in development.
> As to graininess, working with good cotton rag papers should ensure that it only
> arises from overheating the paper after coating and the use of potassium
> chlorate. I find this so offensive that I vary my contrast by using different
> proportions of platinum and palladium in the mix. I have found consistency of PH
> in the papers I use for platinum/palladium from Fabriano and GP inveresk,
> Artistico and Waterford.
I hadn't considered overheating as a possible culprit but its worth
checking out. As for varying pt:pd ratio, I find that for my taste
even a small amount of platinum cools the image color more than I
like. This is the underlying reason for why I now use palladium
almost exclusively. I'll soon be adding step tests for Fabriano
Artistico, Classico, Tiepolo, and Murillo, and Saunders Waterford.
I've never heard of GP inveresk.
> Now I have to work out which buttons to push to download your file.
>
> Did you see my note on papers on 5 February, or have I managed to lose it in the
> system?
I think it must have gotten lost in cyberspace. I don't remember
reading it and its not in my "paper" folder. Would you mind posting
it again. I think this discussion might be of interest to others on
the list so I'm going to CC it to the list.
Keith
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Keith Schreiber
Rights and Reproductions
Center for Creative Photography
University of Arizona
Tucson, Arizona 85721
Fon: 520-621-7968
Fax: 520-621-9444
Email: keith@ccp.arizona.edu
WWW: http://www.ccp.arizona.edu/ccp.html
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