Re: archivalness of gum
On Dec 22, 2007, at 10:44 AM, Dave S wrote:
If there's no paint
called "indigo" that consists of prussian blue and
quinacridone red, then the statement not only isn't "100%
accurate in all cases" but is categorically false.
If it is categorically false, it still does not change a bit of the
sense
that I was trying to say, contextually speaking.
Ummm... How could a categorically false statement possibly be useful
in any context?
Oh, of course, I guess I momentarily forgot that that's how we got in
the mess we're in today in the world, by people making use of false
statements... but that's another subject. But I do understand (and
have understood all along) what you're saying that "indigo" is a hue
name and doesn't refer to a specific pigment, since the pigment PB66
is no longer used in watercolor paint. But the false statement got
in my way. It's kind of like when you're watching a movie about a
place you know and they get something wrong about it; that sticks in
your mind.
I'm going to assume that what you meant to say was that today's
"indigo" is a convenience mixture; you didn't really mean to say
"today's indigo is a mixture of prussian blue and quinacridone
red." The statement that today's indigos are convenience mixtures
is a true statement that I can agree with; why don't we just leave
it at that.
Of course you can discuss whatever you want to discuss, don't be
silly. And if the discussion of hue names didn't have anything to
do with gum printing, I apologize for jumping in. I've been
dipping in and out of this thread while finishing up some things
before going out of town, and maybe missed a turn somewhere. Also, I
don't always read everyone's posts. I was going on the belief, from
some fragments I'd seen here and there, that the discussion of hue
names started with a conversation about pigments relating to a book
about gum printing, which is where I got the idea that it had
something to do with gum printing. My mistake.
Katharine
Hue names are useless for gum printing, because they tell you
nothing about the pigments involved; if you don't know and
understand the pigments you're using, you're losing out on
one of the crucial
control variables of gum printing in my experience. So discussing
colors in terms of hue names just confuses and misleads
people, and I can't see any point in it.
But again, we were NOT discussing hue names for gum printing. Judy
mentioned
about that some names are hue names and not pigment, so I just added
something casually. Come on, Judy and I have known each other for
more than
a decade (I haven't met her in person though), so why can't we talk
about
this things on the list since it is not totally out of topic? Does
everything we say has to be technical details on gum printing?
And Judy later mentioned that we ran a thread about this many years
ago. I
remember that too. I remember saying similar things too, but there
are many
new people on the list, so maybe my background in painting (and the
use of
real gamboge, for example) might be interesting to others.
But that said, I am not going to say that using hue names is totally
pointless. A few years someone on the list mentioned that when he
print his
gum print in monochrome, he didn't use use a black/gray pigment.
Instead, he
uses indigo for one layer and a brown (I forgot which one) for another
layer. It achieves neutral tone but in a more interesting way. Now
in my
mind, I can visualize the effect a little and found that
interesting/beautiful because I have used other colors that way. I
am not
going to say that since he said indigo and certain brown, his
statement was
totally pointless because if I tried to dupicate his effect, my
indigo would
be different from his indigo, and my brown would be different from his
brown, etc. etc. The discussion was not about how to duplicate the
same
thing. It still makes sense and gives a point. Not everything has
to be in a
strict technical sense, and the person does not have to use pigment
names in
order to be considered making a valid point on the list.
Now I don't even know if it would be really more useful if he had
said that
in printing his monochrome works, he use certain PKxx, PBxx, PBxz,
PYzz, and
since he wasn't the manufacturer, he was not sure about the exact
proportion, etc. etc. Not every discussion has to be like that. He
made his
point, and everybody understood it according to the context.
So discussing
colors in terms of hue names just confuses and misleads
people, and I can't see any point in it.
And I do not know how many have been confused by my statement, like
they
didn't know that they could check the pigment names, that they did
not know
the content of prussian blue but oh thank goodness, this super-
knowledgable
fotodave must be the president or at least the head engineer at
Winsor &
Newton, and now he was revealing the secret composition in prussian
blue,
and they follow my statement to the extreme and are now misled and
confused.... :-)
Now I need to get back to my cleaning so that I can be ready for
painting/gum printing. :-)
Dave
The
point is simply I was concurring with Judy that indigo is
nowadays a
hue/tone name. As a mix, each manufacturer is free to use different
pigments in different proportions. One needs to check the content.
As to listing pigment by pigment numbers, that is always true in
another context. But here we are not talking about USING INDIGO
PIGMENT. In fact, the context is the opposite. We are talking about
indigo not being a pigment in manufactured watercolors but
a hue/tone
name.
Dave
-----Original Message-----
From: Katharine Thayer [mailto:kthayer@pacifier.com]
Sent: Saturday, December 22, 2007 10:23 AM
To: alt-photo-process-l@usask.ca
Subject: Re: archivalness of gum
On Dec 21, 2007, at 9:13 PM, Dave S wrote
Same with indigo which originally was made from indigo
plant. It has a
beautiful purple tone, but it is also fugitive. Today's
indigo is a
mixture of prussian blue and quinacridone red. Those who
are used to
true indigo sometimes complain that the synthetic indigo is too
colorful (the true indigo is more muted), but this can be
fixed easily
by adding just a touch of black; so today's indigo is also
a hue name.
Well, yes and no. :--)
The original indigo that was made from indigo plant and
was imported
to Britain from India essentially disappeared around the
turn of the
20th century when it was replaced by a synthetic pigment,
PB 66, also
called indigo, that was supposed to be more permanent than the
original indigo, but proved not to be. But at least it
was easier to
obtain. PB 66 was in use until fairly recently in artist's paints.
Winsor & Newton was the last to use PB 66 in watercolor paints but
discontinued it last year or the year before, so now I no
longer have
to caution people to be extra cautious about paints named
"indigo" to
make sure they don't contain PB66, an essentially fugitive pigment.
Now all paints named "indigo" are convenience mixtures, as
you say,
but it's not true that they all contain the pigments you
name above;
in fact in a quick look through my sources I can't find
any made of
prussian blue and quinacridone red. Do you know of such a paint?
Most "indigoes" are lamp black or carbon black mixed with
a blue; the
blues vary all over the place from pthalo to indanthrone (PB60)
to prussian. For a while a few brands were adding alizarin
crimson,
but none of them do now because of its impermanent nature.
Winsor & Newton adds beta quinacridone to pthalo and lamp black to
comprise their "indigo" but beta quinacridone isn't
quinacridone red
(PB 209), or even quinacridone rose (gamma quinacridone);
it's a deep
bluish purple quinacridone.
This discussion just underscores how important it is to identify
pigments by their number; it's the only unambiguous way of
referring
to pigments.
Katharine
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