Re: Pigments (was: Re: Why Winsor & Newton?

From: Katharine Thayer ^lt;[email protected]>
Date: 06/01/05-04:14:54 PM Z
Message-id: <429E3354.7CD9@pacifier.com>

Eric Neilsen wrote:
>
> Katharine, I am unfamiliar with these authors and their significance to
> testing. Could you give us a couple of book or writing to look at?

1. http://www.handprint.com/HP/WCL/waterfs.html

This is Bruce MacEvoy's site, and my personal favorite. It is so
extensive that though I have spent many hours (days in fact) poring
over it, I keep finding new information there that I hadn't come across
before. As far as I can tell, this guy maintains this site purely for
the love of it; there are no advertisements here for workshops or books
or anything, just good solid information about watercolor pigments, well
organized and solidly empirically based. It is updated constantly, so I
am always reasonably confident that the information is right up to date
as far as changes in brands etc.

2.. Hilary Page's Guide to Watercolor Paints, with updates at

http://www.hilarypage.com/

Here you *will* find advertisements for workshops and books, but also
some good information about colors. But not nearly as deep or extensive
as MacEvoy's site.

3. (This one is somewhat controversial, because he is quite opinionated
about manufacturers and shares his opinions freely, but I find that
refreshing and sometimes amusing, and at any rate have gleaned some bits
useful information here about pigments that I haven't seen anywhere
else, but when he differs with MacEvoy, I go with MacEvoy.)

The Wilcox Guide to the Best Watercolor Paints.

  I keep
> a chart up on my wall with colors that show which pigments are fugitive so
> that students interested in hand coloring can avoid the fugitive colors. I
> also tell them to check into various brands as they are not all made the
> same.

And where do you get the information you use to make this chart? (In
case there's a good source I'm missing.)
>
> What makes them fugitive? And I mean what is happening to the pigment?
> Chemical change or carry off? Do either Page or MacEvoy elaborate on this?

I don't believe either one of them are chemists; my sense is that they
are artists who got into the study of pigments by way of feeling they
needed to know more about the materials they were using. And I can't
answer the question precisely either; I suspect it may be some of both
(chemical change and carry-off).

> What would lead you to believe that embedding them in gum would stop or
> drastically reduce that ageing process?

Nothing leads me to believe this, but I know that some gum printers do
believe that the gum may somehow protect the pigment so that you don't
need to worry about pigment permanence in gum printing the way you do
for painting. My own understanding of the porosity of the crosslinked
gum layer leads me to skepticism on this question. (For example, the
crosslinked gum matrix is porous enough to allow the unreacted
dichromate, pigment and soluble gum to pass through easily into the
water bath).

Trapped beneath layer of gum would
> prevent some motion and help prevent water from passing in and out.

Not necessarily, see above...
>
> And do these pigments have a CAS # or chemical formula that is posted
> somewhere?

I assume the answer to this question must be yes, but I don't know where
--not in any of these sources. I just googled "pigment formulas" and
got nothing much, some stuff about pigments for cosmetics and some
other stuff about ink formulas for printing, and house paints, but
nothing in the first few pages about pigments for artist paints. So if
there's a list of pigments somewhere with formulas, I didn't find it
right off.
Katharine
>
> Eric Neilsen Photography
> 4101 Commerce Street, Suite 9
> Dallas, TX 75226
> 214-827-8301
>
> http://ericneilsenphotography.com
> > -----Original Message-----
> > From: Katharine Thayer [mailto:kthayer@pacifier.com]
> > Sent: Wednesday, June 01, 2005 12:55 PM
> > To: alt-photo-process-l@sask.usask.ca
> > Subject: Pigments (was: Re: Why Winsor & Newton?
> >
> > Hi Eric,
> > Just to make sure we're on the same page-- pigments have of course been
> > widely tested for lightfastness for many years. The American Society of
> > Testing and Materials provides lightfastness ratings for all pigments.
> > It is these ASTM ratings, supplemented by data from independent testers
> > like Bruce MacEvoy and Hilary Page, which give us good information as to
> > whether a pigment, and more specifically a particular watercolor paint
> > made from that pigment, is lightfast or not. So that part, the
> > lightfastness of individual pigments and paints per se, is pretty well
> > established. Sure, there are slight discrepancies between the ratings,
> > but they are usually not great. For example, the paint we were
> > discussing this morning, the Holbein "opera" -- there's no one claiming
> > that this paint is absolutely lightfast. The discrepancy is between one
> > tester claiming that the paint is good to use in spite of not being
> > absolutely lightfast, and another saying that the paint is fugitive
> > enough that it shouldn't be used in collectible art work. I prefer not
> > to use any pigment where there's been a question, but other gum printers
> > of course are free to make their own decisions on this issue.
> >
> > What's not known is whether being encased in gum provides some
> > protection for fugitive pigments, allowing them to fade less. As I said,
> > I'm skeptical, but here we're out in uncharted territory. But I should
> > hasten to say that very many pigments are perfectly lightfast, and if
> > people stick with those they shouldn't have any problem with long-time
> > permanence of their prints. The only question is about the less
> > lightfast ones. As paint manufacturers are gradually phasing out the few
> > fugitive pigments that have held on in watercolor paint, like indigo
> > (PB66) van dyke (PBr8) alizarin crimson (PR 83) gamboge (NY24) etc,
> > the problem of people inadvertently selecting fugitive pigments because
> > they like the color or whatever will become less and less of a problem
> > as time goes on. The more important point being that if people are
> > careful to pick lightfast pigments, they should never have to worry
> > about the permanence of their gum prints.
> >
> > As to Wilhelm, the only mention of pigments in the book refers to
> > UltraStable and EverColor processes. I don't know what testing they've
> > done of these processes since the book came out, but at any rate they
> > don't reveal the pigments, probably due to proprietary concerns. The
> > book says rather cryptically, "The initial UltraStable materials,
> > introduced in 1991, used a non-toxic organic yellow pigment that proved
> > to be significantly less stable in light fading tests than expected
> > based on data provided by the pigment manufacturer. New materials made
> > with a more stable, lead-free, metal-type yellow pigment were introduced
> > in late 1992, but test results for the new pigment were not available
> > when the book went to press." One can guess what those pigments might
> > have been (and didn't I hear that one or both of those companies had
> > gone out of business since then?) but I wouldn't spend a lot of time
> > trying to determine what they are, since we already know a bunch of good
> > lightfast yellow pigments to use.
> >
> > I guess the real question is, why would people insist on using pigments
> > known to be fugitive when there are so many lightfast pigments available
> > in all color ranges? Now if people don't care whether the pigment is
> > lightfast or not, that's one thing. My purpose in educating people on
> > pigments is so that people have the information; if they then choose a
> > fugitive pigment, they are at least making an informed choice.
> > Katharine Thayer
> >
> > Eric Neilsen wrote:
> > >
> > > Has he tested any of the pigments? They are used over a broad range of
> > > mediums and serious collectors would want to know. Curators should be
> > > looking for this information as well or do you think that they just wait
> > > until it fades? Perhaps, Bob has some info on that as he has toured
> > several
> > > plants? Are any of these same pigments being used in the ink jet
> > industry?
> > >
> > > Now pt/pd printing doesn't seems so full of problems : )
> > >
> > > Eric Neilsen Photography
> > > 4101 Commerce Street, Suite 9
> > > Dallas, TX 75226
> > > 214-827-8301
> > > http://ericneilsenphotography.com
> > > > -----Original Message-----
> > > > From: Katharine Thayer [mailto:kthayer@pacifier.com]
> > > > Sent: Wednesday, June 01, 2005 7:52 AM
> > > > To: alt-photo-process-l@sask.usask.ca
> > > > Subject: Re: Why Winsor & Newton?
> > > >
> > > > Eric Neilsen wrote:
> > > > >
> > > > > Where is Wilhelm in all of this? Has he tested any of the pigments
> > > > applied
> > > > > as "intended" or within a gum print?
> > > >
> > > > Don't I wish! But I don't think so..... it seems unlikely that they
> > > > would be interested in this, as so very few people are involved with
> > gum
> > > > printing.
> > > > kt
> > > >
> > > > >
> > > > > Eric Neilsen Photography
> > > > > 4101 Commerce Street
> > > > > Suite 9
> > > > > Dallas, TX 75226
> > > > > http://e.neilsen.home.att.net
> > > > > http://ericneilsenphotography.com
> > > > >
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Katharine Thayer [mailto:kthayer@pacifier.com]
> > > > > > Sent: Wednesday, June 01, 2005 6:04 AM
> > > > > > To: alt-photo-process-l@sask.usask.ca
> > > > > > Subject: Re: Why Winsor & Newton?
> > > > > >
> > > > > > Katharine Thayer wrote:
> > > > > > >
> > > > > > > Christina Z. Anderson wrote:
> > > > > > > >
> > > > > > > > > Christina Z. Anderson wrote:
> > > > > > > > > Now, Holbein does have one color that no other person makes
> > > > quite
> > > > > > > > >> the same--Opera. Can't wait to make a gum with that as my
> > > > magenta
> > > > > > of
> > > > > > > > >> choice.
> > > > > > > > Katharine wrote:
> > > > > > > > > Just so you know, one of the pigments in that paint, basic
> > > > violet
> > > > > > 10, is
> > > > > > > > > fugitive. (The other pigment is PR122, quinacridone
> > magenta).
> > > > > > > >
> > > > > > > > Interesting, but Page gives it 3 stars, her highest rating,
> > saying
> > > > > > > > lightfastness is very good.
> > > > > >
> > > > > >
> > > > > > And as I was saying in a conversation with Henk last week or so,
> > no
> > > > one
> > > > > > really knows for sure whether pigments that are fugitive in
> > themselves
> > > > > > are equally fugitive once encased in hardened gum. I assume that
> > the
> > > > > > answer is yes, so I don't use fugitive pigments. But until someone
> > > > > > actually does that fade testing, we're all just guessing; maybe
> > > > you'll
> > > > > > do those tests, Chris...
> > > > > > Katharine
Received on Wed Jun 1 23:10:45 2005

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