Posted by Tim Bennett on December 6, 2019, 9:46 am
A colleague of mine and I are trying to sort out the color of a sherd recovered from a mid 19th century archaeological site in Michigan. The transferprint has been identified as "Athens" by William Adams & Sons, registered in 1849. The color appears to be black. Photo at https://www.flickr.com/photos/94374719@N08/49170300261/in/album-72157712064675223/
I was wondering if anyone could provide guidance on the differences between black, flow black, mulberry, and purple. I noticed that the search filter on color in the TCC database does not list mulberry. However, in looking at the cover of Ellen Hill's book, Mulberry Ironstone, the transferprint color on the teapot appears the same as the sherd, that is essentially black. In fact, Ms. Hill commented on a post a number of years ago regarding an "Athens" pattern by Charles Meigh that the "type of pottery is called 'Mulberry Ironstone' or sometimes is called 'Flow Black' (a dark version of Flow Blue)." See https://members.boardhost.com/transferware/msg/1349362930.html If this is the case, then why not list mulberry as a search color option?
The color examples on MDA does not list mulberry but has purple and black. As far as purple is concerned, this color seems to be less ambiguous. For example, the TCC database lists a sample of a J. Clementson "Claremont" vegetable dish in purple. It seems fairly straightforward to distinguish between purple and black. However, the confusion seems to surround the use of "mulberry". Is it purple or black? Should the term "mulberry" not be used at all? Not to confuse the issue, but where would gray fit in?
Further, how much "flow" is required to define a ware as a "flow" color. Some patterns that I'm very familiar with such as "Sydenham" by J. Clementson have slight variations in regards to the clarity of the print. However, despite looking at hundreds of samples of the Sydenham pattern over the years, I have yet to see one in blue that was truly intentionally manufactured as a flow color. These variations seem to be more attributed to the quality of the transfer from the copper plate engraving. An article entitled "About the Flowing Process" submitted by George Wells to the Flow Blue International Collector's Club seems to indicate some ambiguity in this regard with comments about how transferprints are blurred.
Thanks in advance for any assistance that might be provided.
The term "mulberry" was likely used to refer to the color imparted to cotton fabrics that were died with the juice of the mulberry tree's fruit. That color would start out somewhere between a dirty pink and a purplish-black, but the reddish components would quickly oxidize to a brownish-black. China collectors have used the term "mulberry" to refer to a slightly broader range of colors, encompassing pinks and reds at one end, earthy browns in the middle, and unadulterated black at the other end. Ellen Hill vehemently objected to the inclusion of pinks, reds and purples on the mulberry palette, but included brown and black, and did not mind if other colors were present so long as they were minor components. Because of the color of fresh mulberry juice, her "definition" would seem somewhat inconsistent with the derivation of the term "mulberry."
Ellen also made the point that her book on "Mulberry" made no issue of "Flow," even though the majority of collectors refer to "flow mulberry" as opposed to simply "mulberry." When reminded that black transferware is virtually never called "mulberry," even by her, and that she included flowing black patterns in her Mulberry book, and that this was inconsistent with her claim that "mulberry was independent of flow, Ellen would just shrug. I would remind you that technically, definitions are determined by usage, though not necessarily by the first person to write a book on the subject.
If you want to approach the question of mulberry color from science, start with the facts that many of the metal oxides that are used to formulate these ceramic-decorating colors have multiple oxidation states, that kiln atmospheres are either oxidative or reductive depending on the fuel-to-oxygen ratio in use, and that these two facts make the end color results variable and difficult to control. Then know that, generally speaking, mulberry colors start with manganese oxide, and are variously modified (by the potter) by the addition of copper, iron, nickel, chromium or cobalt oxides, most of which experience color change as the kiln atmosphere changes, and most of which behave somewhat differently when exposed to so-called "flow powders." This can result in a printed image in one color surrounded by a "flown" halo of a different color.
As for specifying a required amount of flow, the closest you might come to having that sort of criterion would be that there must be some sort of visible "halo" surrounding the printed or hand-painted decorations. Not under magnification, but readily visible to someone with eyesight approaching normal. It would be impractical to attempt to instrumentally qualify "flow". We simply have to live with the fact that some examples will fall squarely on top of wherever we draw the line, and in those cases we may have to agree to disagree.
As for the Athens-by-Adams sherd you questioned, this pattern is agreed upon by the FBICC members empowered to make such calls to be a mulberry pattern (the color being predominantly black) and that it is a flowing example. After having been in this field for about 50 years, I can say that I have never seen this pattern that did not have some flow, but also that no examples that flowed heavily were ever seen. I believe that Adams used a minimum amount of "flow powders" in the glaze formulation he used for this pattern to achieve such a mild flow, though a similarly understated effect could have been caused by including in the color formula only a modest amount of the metal oxides that flow. (Many coloring oxides cannot be made to flow in the "flow powder" manner.)
One last point: Your "... 'Flow Black' (a dark version of Flow Blue)" is a misleading statement. Cobalt oxide is black, but it cannot flow and remain black. Cobalt oxide only turns blue when it successfully dissolves into a silica-based glaze. Flow blue is made by making cobalt oxide flow. "Flow Black" would have to be made using manganese and nickel oxides, or some other combination that would be both black and able to be made to flow.
Many thanks for the detailed explanation, that is very helpful and much appreciated! Also thanks to the FBICC members that also contributed.
The first paragraph in your reply regarding mulberry and some of the ambiguity surrounding the hue definition make sense. We have a large mulberry tree just behind our house. The berries are basically black but when stepped on by barefooted kids the color of their feet is stained purple...
Your comments on the background science of the colors is actually somewhat familiar to me as I have been a studio potter for quite a few years though I definitely still consider myself a student. I make wheel thrown pottery and early on I decorated vessels with cobalt firing at cone 10 (2345 F) reduction. I found that the use of cobalt is tricky in several regards. If applied too thickly, it would turn black and even 'pop' out of the glaze. Also, care must be used not to spread it all over other wares. Small quantities on fingers left finger prints and I even had an impression on other pieces due to clumsy handling.
In reading your article, "About the Flowing Process", I was intrigued about the mention of ghost images. In studio pottery, I believe the same process is referred to as transmutation, but we typically see it with copper based glazes and I have a few of my own creations with this phenomenon. In addition, I have a couple 19th century non-flow pieces that clearly ghosted/transmutated to others. One is a London shaped dipped ware with blue bands. The bands on the interior clearly don't line up with the exterior. Another is a plate with blue sprigs. It exhibits ghosting on the reverse that also don't line up with that of the front. I'm interested to know if you think non-flow pieces such as these may have been included in saggers with flow pieces as the reason for ghosting/transmutation or was caused for entire different reason.
I was also wondering what your thoughts might be on the use of the term "pearlware". This term is commonly used by collectors but also found in literature. As far as I have seen, contemporary manufacturers/importers/retailers never referred to wares as "pearlware". It is true that some manufacturers did use variations of "pearl" in maker's marks such as "pearl stone", "opaque pearl", etc. The conventional thought is that small amounts of cobalt were added to the clear glaze to achieve a whitening effect. My understanding is that "pearlware" is defined by blueish pooling of glaze, typically at the oblique edges of the foot ring. We conducted EDS/SEM on a number of sherds dating from the 1830s to 1850s but only a couple had the slightest amount of cobalt. How blue is "blueish" and when does "pearlware" end? I have pieces in my comparative collection from the 1850s-1860s that have bluish pooling of the glaze in the foot ring but I doubt many would include those as "pearlware". From a studio pottery standpoint, glaze hue/application, is generally not a good indicator due to the variability of glazes, glaze application/thickness, body type, firing temperature, firing schedule, contamination, etc.
Hi Tim, First comment is on "popping out of the glaze". Both cobalt oxide in flow blue and manganese oxide in mulberry can rise to the surface and create a sintered effect. In the case of cobalt oxide, it is usually just the original oxide that surfaces, probably due to its concentration in the glaze phase exceeding its solubility therein. IN the case of mulberry, the manganese oxide can actually be reduced to metallic manganese, leaving a decidedly metallic surface on the glazed ceramic body, though the reason is again a supersaturated solution, the pigment "precipitating" to the surface instead of the bottom of the solution layer.
As for "ghost" images, the unassailable proof is found on those pieces that have a different "ghost" image on the reverse side than the image on the front of the piece. This proves twice, both that there were differently decorated items stacked together in the saggar, and that the ghost images communicated from the transferred decoration, not through the pottery but through the atmosphere above it to the adjacent pottery. That is a rather powerful concept once you grasp its full significance. The physical chemistry involved is comparable to quantum mechanics.
As for non-flown items having ghosts, as long as there was a glaze on a nearby piece that was receptive to the volatilized cobalt, ghosts can appear anywhere. (The actual chemical specie responsible for that "transmutation" (it is really "transportation", as nothing has been transmuted) is only speculated as far as I know, since there is no way to analyze a specific compound at kiln- firing temperatures.
As for "pearl" and "pearlware", they are two different animals, the first having derived from the second, but "pearl" is used as a tradename in this context, while pearlware refers - as you note - to dirty greenware that has been intentionally tinted blue, as "bluing" tints dingy cloth to "whiten" its appearance. When better, more pure raw materials used to make greenware became available, whiter greenware was the result, and less and less cobalt oxide was needed to make it LOOK white. Thus the arrival on the scene of "whiteware". At what point, precisely, does pearlware transition to whiteware? ROUGHLY, around 1840, though some very white greenwares were being produced in 1830, and some very dingy greenwares were still being made in 1850. Not every potter bought his raw materials from the same source. The "pooling" of the glaze is a reasonable measure, not in how much glaze pools, but in how much blue tint is evident in any place that the glaze is thick enough to sense its color.
By the way, I type with TWO fingers, and it isn't fast, but I can talk at just under the speed of light, so if you have a lot of questions, I'm at 757 427 3619, and I'm retired, so I have plenty of time if you want it.