U of S | Mailing List Archive | alt-photo-process-l | Re: archivalness of gum

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.

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. :-)


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



-----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
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


to pigments.