Re: Gum problem(s)

From: Katharine Thayer ^lt;>
Date: 11/18/05-07:09:03 PM Z
Message-id: <>

Thanks for response, that's interesting. I'd just never heard anyone
give that advice before, but I agree that it's probably good advice for
beginners. I don't think my problem in the beginning was too thick a
coating, but too much pigment in the coating, but the effect re reading
print through it would be the same. Thanks for dialogue,

On Nov 18, 2005, at 4:54 PM, Tom Sobota wrote:

> Yes, by all means test it for yourself. However please keep in mind
> that
> this was only said and meant as advice for a beginner.
> 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.
> "Who says" you ask. To tell you the truth I don't remember. I read it
> in
> a couple of different places years back. When I find it again I will
> tell you.
> Anyway it has been useful for me in a time long before Internet, when
> there was nobody to ask.
> What is important is perhaps not this test but the fact that the coat
> should
> be rather thin and keep a certain transparency at all times. This fact
> is well
> attested in the bibliography:
> "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.
> Tom
> At 21:53 18/11/2005, you wrote:
>> Second thought:
>> I sent something through a while ago, questioning the advice about
>> coating so that you could read text through the coating. That post
>> hasn't found its way back here yet, but I've been thinking more about
>> what I said, and decided I don't necessarily agree with myself.
>> After all, I've always been a great one for printing with transparent
>> pigments, and no doubt you can see the previous print through
>> subsequent coatings on a tricolor print, even (very dimly) the cyan
>> layer which for me goes on last. Even a very dark color that's
>> transparent, say ivory black, is transparent enough that I wouldn't
>> be surprised if you could read a newspaper through it, even though it
>> can print as dark a value as lamp black can.
>> In my previous comment, I was think not of transparent layers but of
>> a coating intended to produce a one-coat print, like lamp black or a
>> blue-black or brown-black that you might use for this purpose, and I
>> still wonder about that, but like I said, I'd have to try it for
>> myself.
>> kt
Received on Fri Nov 18 19:10:21 2005

This archive was generated by hypermail 2.1.8 : 12/01/05-02:04:50 PM Z CST