George,

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.

Thanks for any insights you might offer.

Tim Bennett
Warner Pioneer Homestead