On Sat, 19 Nov 2005, Tom Sobota wrote:
> Beginners, and I was no exception so I know, mostly tend to coat too
> heavily. In this context, the "newspaper test" is useful, I think.
A propos of that newspaper test -- yes, I've read it in several old
manuals & articles. But IF they really did it then, I think we'd have to
modify the operation to do it now.... because the papers we use are so
heavy that even with the brightest light under them and no pigment I doubt
we could read much if any newsprint through them.
Demachy & co printed on a paper called cartridge paper, or like that --
about what we'd call typing paper today.
So you could coat your emulsion onto typing paper and give it the
newspaper test, but I suspect that the idea suffices.
J.
> "If the coating appears to be dark enough to completely hide the paper
> from view, then it's either too thick or too much pigment has been used."
> ("Historic Photographic Processes" , Richard Farber, 1998)
>
> "The paper is covered with a thin coat of this mixture, so that the paper
> can still be seen through the color..."
> ("Manuale prattico e ricettario di fotografia, Rodolfo Namias, 1914)
>
> "Dieselbe (die Mischung) muss so dünn aufgestrichen werden, dass
> das Papier noch durchscheint..."
> ("Das Pigmentverfahren, der Gummi-, Öl- und Bromöldruck und
> verwandte photographische Kopierverfahren mit Chromsalzen"
> Josef Maria Eder, 1917)
>
> and many others. The "newspaper test" is only a simple method to
> check the transparency of the coat before applying it.
>
> But I think that it was originally meant for checking the dark colours
> usually used for one coat printing. The transparent colours used for
> trichromy are ... well ... transparent.
Received on Thu Dec 1 00:03:19 2005
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