Very well-thought out reply by George and very polite. I might suggest that the proposed colorimeter project would be akin to classifying snowflakes...virtually no way possible to control the inherent variability and as George underscores, it is decoration, not wear type that is of greatest value to archaeological interpretation.
-----Original Message-----
From: Nancy S. Dickinson <[log in to unmask]>
To: HISTARCH <[log in to unmask]>
Sent: Wed, Feb 22, 2012 12:37 pm
Subject: Re: Colorimeters and Spectrophotometers on Ceramics
George,
Hazzah! I hope you put this in a CNEHA journal, at least. It should be a
tear-out page in a SHA publication. I'm trying to think of a title for
it, although your pigment of our imagination works so well. For Pete's sake
and for repeat's sake....
Maybe something about bringing a dead horse to water OR OR OR
Nancy
In a message dated 2/22/2012 10:45:54 A.M. Eastern Standard Time,
[log in to unmask] writes:
Colleagues,
Pearlware has become a pigment of our imagination!!! I have been beating
on this horse since 1980 and not making much progress. We have made
pearlware into something much more important than it was to the potters and
merchants dealing with these wares. Wedgwood’s term “Pearl White” has
morphed into pearlware, a term that the Staffordshire potters and importers
almost completely ignored. There were at least six different formulas for
“pearl body” in the Wedgwood records from 1815 to 1846 (Miller 1980:17).
The use of the term “pearl” as part of maker’s marks occurs from at least
13 potters, all of which date from between 1834 and 1893 (Miller
1980:19). Pearl
white was Josiah Wedgwood’s term for these blue tinted wares, but the other
potters referred to the ware as “China Glaze” and it appears that their
use
of that term predates Wedgwood’s Pearl White. There are a number of
advertisements and invoices that describe wares as China Glaze in the 1780s
into the first two decades of the 19th century, but the listing of
“pearlware” is very rare (Miller 1987:91-92). The term pearlware does not
show up in probate inventories. Pearlware does not replace creamware;
decoration replaces creamware. None of the Staffordshire potters’ price
fixing lists from 1783, 1787, 1795, 1796, 1808, 1814, 1825, 1845, 1853 and
1859 list pearlware or China glaze. The wares are listed by their
decorative types, i.e. CC, edged, painted, dipt, or printed (Miller
1987:90). CC in the early period was for cream colour, while later it is
much whiter and signifies undecorated wares. The 1784 edition of *Bailey’s
Directory of the Potteries of Staffordshire* lists ten potters that
describe themselves as producers of China Glaze and Cream Colour ware
(Miller and Hunter 2001:148). Pearlware is not listed after any of the
potters’ listings of what they produced.
The takeoff period for these blue painted and tinted wares appears to be
after Roger Kinnaston set up a furnace in 1772 for the refining of cobalt
in Cobridge, Staffordshire (Miller and Hunter 2001:143). These early blue
painted China Glaze wares are almost always painted in Chinese style
patterns and the blue tint is very obviously an attempt to imitate Chinese
porcelain. Later the bluing added to the glaze was limited to the amount
to make the ware look whiter and one must look for the tint of blue in
areas where the glaze is thicker such as around footrings. Thus, the
intent of the potter in the use of cobalt in the glaze evolved over time
(Miller 1993:4-6). Any attempt to set a fixed definition of pearlware will
produce a product that is locked in time and not reflective of the
evolution of the use of cobalt to affect the glaze tint from a visible blue
to a white ware, much as bluing is used to make laundry white.
Dating pearlwares by ware type is much less useful that by decorative
styles such as the rococo shell edge versus even scalloped shell edge,
Chinoiserie China Glaze wares or polychrome floral painted provides much
better dates. Undecorated pearlware sherds almost all come from decorated
wares such as the centers of shell edged plates or to painted teawares. In
short, ware types are of minimal use for dating contexts.
Creamware, like what archaeologists are calling pearlware, also
went through an evolution from a rather dark cream in the mid-18th century
into a rather whiteware by the 1820s. Where it stops being creamware and
becomes CC ware or a white ware is an arbitrary decision that may not be
very meaningful. Bill Liebeknecht makes a very telling point when he
described yellowware sherds from the Coxon Pottery waster dump in Trenton,
New Jersey. The differences in the yellow color caused those who are
familiar with these wares to classify some as being from New Jersey and
some being from Ohio. Bill also makes a point that CC wares were being
produced in Trenton well into the 19th century for such wares as chamber
pots. Using 101 importers’ invoices dating from 1806 to 1886 it was
possible to show that CC tea wares stopped being sold much earlier than CC
ware plates and that CC ware bowls continued to be available through the
whole period of 1806 to 1886 (Miller and Earls 2001:84-87). No doubt the
CC wares listed in the later invoices would be classified as whitewares by
archaeologists.
Like I said, I have been beating this horse since 1980. But keep beating,
it is still dead.
References:
Liebeknecht, Bill
2012 HISTARCH posting February 20th.
George L. Miller
1980 Classification and Economic Scaling of 19th Century
Ceramics. *Historical Archaeology* Vol. 14:1-40. See appendix A
“Pearlware in the 19th Century” pages 15-19.
1987 Origins of Josiah Wedgwood’s “Pearlware.” *Northeast Historical
Archaeology* Vol 16:83-95.
1993 A User’s Guide to Ceramic Assemblages Part Four: Some Thoughts on
Classification of White Earthenwares. *Council for Northeast Historical
Archaeology Newsletter* November 1993, Number 26: 4-7. Available for free
download on the CNEHA website.
George L. Miller and Amy C. Earls
2008 War and Pots: The Impact of Economics and Politics on Ceramic
Consumption Patterns. *Ceramics in America 2008*: 67-108.
George L. Miller and Robert Hunter
2001 How Creamware got the Blues: The Origins of China Glaze and
Pearlware. *Ceramics in America 2001* pages 135-161. Can be downloaded
from
http://www.chipstone.org/publications/CIA/2001/MillerHunter/MillHuntIndes.ht
ml
On Mon, Feb 20, 2012 at 3:47 PM, scarlett <[log in to unmask]> wrote:
> Dear Chris,
>
> The list has provided you with some excellent advice. i am skeptical
that
> this will be very interesting in the long run, but that is exactly what
> makes it interesting to do now! I wrote an entire MS thesis after a
> professor (like me) told me (as a student like you) that some technical
> study of historic ceramic wouldn't work. It worked fine and was
> interesting. He was wrong. I may very well be wrong.
>
> I would add this advice for you-
> The standardization of color is critical in industrial pottery
> manufacture. Consistent color is required for matching sets of
tableware.
> Those that came from the kiln whole, but slightly off, were sold as
> seconds, thirds, fourths, or even fifths or sixths. Consumers ideas
about
> the closeness of color matching changed over time.
>
> Once you understand this, you can expect that the industrial process
> engineers that work with ceramic have probably used tools like these for
> many decades. While antique collectors will swear to you that they can
> tell the difference in two Spode china plates that were fired with North
> Sea Gas vs. gas from the continent, engineers tend to be more data
driven.
>
> I expect that if you dig into the ceramics engineering literature, you
> will find some comparative data on the variability of color by kiln load
by
> factory.
>
> I don't think IUP has any engineering faculty. You could get advice by
> contacting Dr. William Carty, Ceramic Engineering Program Chair and
> Professor of Ceramic Engineering at Alfred University in New York. He
> would probably be able to direct you to someone who knows that part of
the
> business.
> http://engineering.alfred.edu/facultyandstaff/
> Be sure to explain your research question by email, since most engineers
> and materials scientists that work in ceramics can study everything from
> superconductors to nanoscale glass!
>
> Cheers,
> Tim
>
>
> On Feb 20, 2012, at 2:39 PM, John Chenoweth wrote:
>
> > Dear List,
> >
> > A friend just pointed this thread out to me. I’m sorry I haven’t
chimed
> in earlier.
> >
> > As it happens, I’ve just been working on this question over
> > this winter, spending some time collecting about 2,000 points of data
> with a
> > spectrophotometer on cream, pearl and whitewares.
> >
> > Spectrophotometers are much like colorimeters, but whereas
> > colorimeters simplify color to tristimulus values (L*a*b* values often,
> akin to
> > hue, chroma, and value that we all know from Munsell)
spectrophotometers
> > capture the full spectrum of reflectance at each wavelength. These
can
> produce tristimulus values through
> > a simple conversion, but the latter are not as accurate because of the
> > phenomenon of “metamerism” in which two different colors look the same
> (i.e.
> > produce exactly the same colorimeter results) as a result of the light
> used to
> > examine them.
> >
> > I obtained a portable spectrophotometer that was extremely
> > easy to use, although its cost is prohibitive for normal analysis.
That
> shouldn’t be an issue, really, since I
> > don’t think the goal of this work will be everyone using machines to
> identify
> > the color of every ceramic: rather, we need a better understanding of
the
> > actual variations of color present and some statistical analysis that
> can point
> > us to how to deal with that variation. So, for instance, we can ask if
> divisions into cream, pearl, and white
> > are “real” and what kind of margins of error there are in these
> determinations.
> >
> > In addition to the divisions (or lack thereof) of cream,
> > pearl, and whitewares, I’ve been looking at the question of if
> metamerism is an
> > issue, and how much of an issue (we never see people discuss the
> conditions
> > under which they make their identifications, do we? Yet artificial f.
> natural light makes a huge
> > difference in appearance!). These values
> > can also be converted to precise Munsell values (no margins of error
> between
> > the chips; these are mathematically produced so you get values like
3.4Y
> > 8.9/1.71), so that we can consider earlier attempts to define ceramic
> color
> > (but without the well-known problems of Munsell, such as source-light
> variation
> > and large differences between each individual’s determinations).
Also,
> we know that color can vary across vessels,
> > yet we haven’t quantified by how much.
> >
> > Of course, George Miller’s comments are very central to
> > this discussion (not surprisingly!). I
> > think, as he will probably agree, the question of defining a “master”
> value for
> > each of these types is probably not going to happen: as he points out
the
> > potters all did different things, resulting in a range of values.
> Ultimately, Carl Steen is also right that
> > many other factors go into determinations.
> >
> > BUT, and here is why I think projects like this are
> > worthwhile) we can actually measure most of these factors using
> repeatable (I’m
> > too much of a post-modernist to say “objective”) procedures and
> equipment:
> > spectrophotometers, glossimeters, durometers, etc. We all make all
> these determinations all the
> > time, but, as Bill Liebeknecht points out with his yellowware story,
we
> aren’t
> > always sure of what we’re talking about. Fifty years of experience can
> produce consistency, but it can’t
> > reconcile with another person’s fifty years of experience. The
> conversation has been too long about “is
> > that yellow enough to be…” and can now be a discussion of what a
> particular
> > level of yellow (repeatably measured) means. This doesn’t solve our
> problems, but it means we’re speaking the same
> > language when we have our discussions, at least.
> >
> > Finally, I’m sorry to say that all this is prologue,
> > since I collected the data in question two months ago, but have yet to
> finish
> > the statistical analysis (must meet up with a friend who is better at
> > multivariate stats than me!). At first
> > glance, the data rather suggests that there are no clear distinctions
> between
> > cream, pearl, and whitewares on the basis of color alone, but the issue
> of
> > exactly how meaningful those classifications are is yet to be settled.
> >
> > I look forward to reporting the results soon!
> > Best,
> > John
> > ----------
> > John M. Chenoweth, PhD, RPA
> > Post-Doctoral Fellow, IHUM
> > Stanford University
> > [log in to unmask]
> >
> >
> >
> >
> > ________________________________
> > From: sent <[log in to unmask]>
> > To: [log in to unmask]
> > Sent: Monday, February 20, 2012 9:20 AM
> > Subject: Re: [HISTARCH] Colorimeter for ceramics
> >
> > All depends on the questions you wish to ask.
> > Once ceramics enter secondary contexts these sort of distinctions
become
> > less important
> > As they decline in importance with context change then essential
material
> > attribute description becomes more important.
> >
> > Conrad Bladey
> >
> > -----Original Message-----
> > From: Bill
> > Sent: Monday, February 20, 2012 8:25 AM
> > To: [log in to unmask]
> > Subject: Re: Colorimeter for ceramics
> >
> > I agree with Carl. When looking at an assemblage you should be more
> > concerned with the larger picture. What are the other ceramics found
in
> > association. You can take a piece of white paper and layout the
> pearlware
> > and creamware sherds and make divisions rather quickly. Creamwares or
CC
> > wares were being produced in Trenton as late as 1905, specifically
> > chamberpots. This just goes back to my point about the association of
> the
> > wares in context.
> >
> > Bill Liebeknecht, MA RPA
> > Hunter Research, Inc.
> >
> > -----Original Message-----
> > From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]] On Behalf Of
Carl
> > Steen
> > Sent: Monday, February 20, 2012 7:59 AM
> > To: [log in to unmask]
> > Subject: Re: Colorimeter for ceramics
> >
> > Glaze tint varies for many reasons. While early cream and pearlware do
> have
> > distinctive colors, this varies due to a number of factors ranging from
> the
> > potters glaze formula, and firing conditions, to use and deposition
> history.
> > Also, don't forget that blue and cream tinted wares were intentionally
> > produced throughout the 19th and 20th centuries. I can't tell you how
> many
> > times I have seen single sherds of creamware or pearlware identified in
> > otherwise late contexts. Glaze tint is only one of many characteristics
> > (density, firing, decoration, vessel form etc) you have to look at to
> > accurately date a vessel or sherd, so micro-analysis of glaze tint is
> > something I wouldn't get too hung up on, personally. But do keep us
> apprised
> > of your results! Carl
> >
> >
> >
> >
> > Carl Steen
> >
> >
> >
> >
> > -----Original Message-----
> > From: Conrad Bladey <[log in to unmask]>
> > To: HISTARCH <[log in to unmask]>
> > Sent: Mon, Feb 20, 2012 7:49 am
> > Subject: Re: Colorimeter for ceramics
> >
> >
> > Color is often formed my after market environmental conditions I would
> > suggest
> > chemical analysis more helpful but that too. Would be modified by soils
> and
> > heat
> > etc.
> >
> > Conrad
> >
> > ----------------------------
> > This message has been written by fingers that are too big!
> >
> > On Feb 20, 2012, at 6:56 AM, Bob Genheimer <[log in to unmask]>
> > wrote:
> >
> >> Chris
> >>
> >> I just completed a large scale examination of Cincinnati-area yellow
> ware,
> > and
> > utilized a full-color Munsell book(s) for color comparison. The
Munsell
> is
> > not
> > fully adequate, because there is still a small range of color within
each
> > chip
> > match. I recognized that a colorimeter was the way to go, but taking
> > hundreds
> > of vessels to the colorimeter was just not an option. I would be very
> > interested in comparisons of colorimeter data with Munsell matches.
> >>
> >> Bob Genheimer, RPA
> >> George Rieveschl Curator of Archaeology
> >> Cincinnati Museum Center
> >> 1301 Western Avenue
> >> Cincinnati, Ohio 45203
> >> 513-455-7161 office
> >> 513-846-4898 mobile
> >> 513-455-7169 fax
> >>
> >>
> >> -----Original Message-----
> >> From: HISTORICAL ARCHAEOLOGY [mailto:[log in to unmask]] On Behalf Of
> > Christopher Nicholas Marini
> >> Sent: Sunday, February 19, 2012 3:47 PM
> >> To: [log in to unmask]
> >> Subject: Colorimeter for ceramics
> >>
> >> Dear List,
> >> I am a graduate student at Indiana University of Pennsylvania and I
am
> > currently looking to begin work on my master's thesis. The project I am
> > considering involves using a device called a colorimeter, which
measures
> > color,
> > to develop a scale for identifying ceramics, most notably creamware,
> > pearlware,
> > and whiteware, as I have had personal experience with the difficulty in
> > identifying these artifact types.
> >>
> >> I have done some research into this topic, but am unsure whether or
not
> > anyone
> > else has already attempted it. I have looked through several major
> journals
> > and
> > have not found any reference to such a project. If anyone knows of work
> of
> > this
> > type that has been done, please let me know of it so that I may
> incorporate
> > it
> > into my project or switch thesis topics.
> >>
> >> Thank you for your time,
> >> Chris
> >>
> >>
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