Earthenware Experiment- What Went in the Kiln

As I mentioned in one of my earlier sporadic blog posts, I have been playing with earthenware in the studio lately. It's been something in the back of my mind for years to try earthenware in a wood kiln. This is mostly because through my kiln furniture research I knew that many early stoneware potters were also making earthenware, but all in the same kiln. So, the biggest quandary I had was what would earthenware look like in a salt kiln environment?

After spending a day cleaning the kiln and shelves last week, the kiln got loaded up last Friday and the fires started on Sunday.

I used the marbled technique that I recently made a post about both on lids and on the sides of some mugs. All of the pots in the photos to come have been bisque-fired, so these are not the finished products.

I ended up having an issue with a white slip that I tested. It may have been a reaction to the clay I was using at the time of the slip tests (Highwater Lyman Red), but either way, I ditched it because I could not keep it from cracking and flaking. I did fired several bowls that had cracking just to see if the flux (3134 Frit) in the slip would heal with a glaze in the kiln. We shall see.

I switched to a very basic white slip and started using Highwater's Earthen Red clay, which I thoroughly enjoyed throwing with. I kid you not, it's like chocolate pudding between your fingers. The switch proved worthwhile and I had a smooth slip that dried well and played nicely even after the bisque firing.

I am testing several clear glaze recipes. One recipe uses mostly white clays as its base, so it turns a very white color after glazing. The other is basically 3134 Frit and Redart, making for a brown-looking glaze.

I played around a little bit with some manganese, by sifting some raw manganese on top of the glazed surface, and sponging it after mixing it with a white slip. The mugs above have lines of sponged manganese and green slip. I anticipate a deep purplish brown/black, but will wait to see what actually turns out.

Other decorated wares included a few squared bottles and some slip trailed and marbled dishes. I was really excited to see how those turned out in the bisque kiln, and am hopeful for their survival in the firing.

You might think I sound a little pessimistic about how this all might turn out. I'm not pessimistic as much as I am hesitant. There's not really a lot of people wood-firing earthenware here in the states and I think it has a lot to do with our restrictions on lead usage. Lead and lead variants like galena are very forgiving in their fluxing and melting temperatures. They don't craze a bunch, or have major reactions like pitting, flaking, or pin-holing. Those things are what I have heard can happen with earthenware in a wood kiln, particularly if it reduces. As one potters once told me, "it's hard to keep a wood kiln out of reduction" and my kiln has that very issue. We didn't seem to have a lot of reduction during the firing this go-around, but will not really know until we open it up.

So, fingers crossed, I teamed up with Anne Partna from Blue Hen Pottery and together we made enough pieces to fill the kiln. Here are some photos of the stacks in the kiln:

I did an overnight gas preheat, which I have found heats the kiln up to around 225 (F), dries out the interior, and starts to heat the brick up. Heating the brick up seems to be what takes the longest with this kiln because I used all hard brick. The more the brick is heated up, the faster the kiln will roll to the end. The firing proved to be a little lengthier than we were anticipating, but it was still not as grueling as a stoneware firing. We are unloading later this afternoon, so stay tuned!

Decorating Technique- Marbling on Lids

I've always loved marbled paper. I vaguely recall making some when I was younger, and always love to open really old tomes with marbled paper on the interior of the books.

I made these lidded jars that were similar to the lidded jars I started with the 52 form project (not totally defunct, mind you!), except these jars are earthenware. I'm working toward an experimental firing this month with earthenware in my wood kiln (that has heavily salted walls!).

White slip in bowl

Dots of colored slip on surface

For these jars, I thought it might be fun to see if I could marble the lids. I took a shallow, wide bowl and put about 1 inch of white slip into the bowl. I then dotted the surface with red and green slip.

Bamboo skewer

zig-zag dragging of the bamboo skewer through the slip

Taking a bamboo skewer, I dragged the skewer through the slip in order to create a marbled look (I basically moved the skewer slowly across the surface in a zig-zag pattern).

Greenware lid

Going for the dip

Then I took the lid, flipped it over, and dipped it into the surface of the slip, pushing slightly until the slip reached the edges of the lid. The lid and the body of the jar were in the green state- so not bone dry, but not wet, just right in the middle.

Ta da!

Voila! It didn't pick up the marbling as I thought it would, but it made for a really fun pattern! Here is another attempt with just red and white slip:

With one bowl of slip I found I could do about 4 lids before the slip became too muddled and needed to be refreshed. I am excited to see how these might turn out in the upcoming wood-fired kiln!

Earthenware Kiln Furniture

In taking down the exhibition at the North Carolina Pottery Center, I had a few moments to handle and ponder over the earthenware kiln furniture that was on display. As esoteric as kiln furniture may be, it is an incredible insight into pottery production. When I look at kiln furniture, I don't just get excited about the individual fingerprints that usually cover the surface, I see in my mind how the pots were stacked in the kiln using each piece. That may sound a little weird, but that is how my brain works- see a piece of kiln furniture, see a stack of pots. Or else you can watch my eyes shift around as I study the kiln furniture while I am trying to stack the pots in my brain.

These particular pieces come from the William Dennis site in Randolph County, North Carolina. This also happens to be the same site where Hal Pugh and Eleanor Minnock Pugh have their pottery shop, New Salem Pottery. Drawing from their text panel in the exhibition, here is a little background on the Dennis potters:

Located in North Central Randolph County, NC, the property was settled in 1766 by the Thomas Dennis Family who along with other Quakers had relocated from Chester County, Pennsylvania. The property sat astride the Trading Road (formerly the Indian Trading Path) which extended from Petersburg Virginia into South Carolina. The location and the existence of large beds of earthenware clay made it ideally suited for a pottery. William Dennis (b.1769) and his son Thomas (b.1791) were the earliest documented potters working at the property. William, a Quaker opposed to slavery, apprenticed George Newby, a 12- year old African-American youth, to learn the pottery trade in 1813 which lasted nine years until 1822.  Archaeological evidence and extant collections reveal that the Dennis potters not only made simple, utilitarian lead-glazed earthenware, but also a variety of decorative slipwares and thinly turned tablewares. William moved to Indiana in 1832, selling the land where the house and pottery stood to Peter Dicks, a Quaker businessman and potter who lived in the nearby community of New Salem.

The site was discovered in 1974 by Hal and Eleanor after plowing a garden spot. After several years of research the site was identified as belonging to the potter, William Dennis. In November of 1997 Tom Hargrove of Archaeological Research Consultants, Inc. conducted non-evasive geophysical surveys at the William Dennis site to determine its subsurface integrity. A very distinct classic kiln signature was shown to exist and a decision was made to focus on a test excavation at the kiln site. Fieldwork began in March 1998 and excavations were done by Dr. Linda Carnes-McNaughton and volunteers. Units confirmed the anomaly or feature at the Dennis kiln site was the foot print of a 10 by 10 foot square kiln constructed with two foot thick fieldstone walls and lined with brick.  This square design, which is the first excavated in North Carolina, appears to be of Quaker tradition.  Two later examples of this style of kiln have been found in NC at Quaker pottery sites.

Earthenware kiln sites, particularly early, have the closest thing to a contemporary kiln shelf used in the firing. Predominantly, large, flat pieces of clay do not show up in stoneware kiln sites, and show up in incredible numbers in earthenware sites. I think this has more to do with the fact that salt adheres better to large, flat surfaces, so having fewer contact points provided for a better firing. Some stoneware sites I have looked at do have a few of these slabs of clay, but nowhere in the numbers as they show up at earthenware sites. 

These pieces in earthenware kilns, though, are not as large as contemporary shelves. They tend to be made in much the same way that roof tiles are made (slabbed out, certain thickness, certain width, and texture on one side). They end up being longer than they are wide. They also sometimes have grooves on one side (like roof tiles), made either with fingers raked across the surface or a tool. This provided for less contact points too, because even though salt was not used, the glazes sometimes ran, and some pots were fully glazed (meaning the exterior of the foot was glazed). In Bethlehem, Pennsylvania, the Moravians there were literally using roof tiles, with the cut out holes, or tabs for hanging the tiles, still on the piece, but clearly stuck in the kiln between a few pots. That example may also reveal how roof tiles were fired.

Rim on the kiln furniture

Rim on the kiln furniture (same piece as above)

 As in the photo above, you get a chance to see parts of a pot adhered to the kiln furniture because a glaze ran. 

Then you also have examples where two tiles are stuck together. It's moments like these when contemporary potters can be empathetic for historical potters. Think of when a glaze has totally run off on you, destroyed a shelf, or destroyed another pot.

In other notes, I am back in the shop this week, rampantly working to get pots finished for loading the kiln next week!

For more information on the Dennis site and the excavated material, see the 2010 Ceramics in America publication with an article entitled "The Quaker Ceramic Tradition in Piedmont North Carolina" by Hal and Eleanor. As an exciting note to end on, this year the William Dennis site was approved for the National Register of Historic Places.

Kilns Gone Wrong

Earthenware separating bars, Piercy Pottery site. Courtesy, Alexandria Archaeology Museum

There are archaeological sites where evidence of the production of stoneware and earthenware are found. Often these sites are called "transitional" with the implication that the potters were moving from working with earthenware to stoneware. However, my thoughts are that many of the potters, particularly in regions with less potters, or with higher levels of competition, met the market demands by making both either simultaneously or attempting to make both at some point in their production. For example, the William Rogers site in Yorktown, Virginia was making both stoneware and earthenware. There are certainly numerous sites where the potters did in fact move from earthenware to stoneware, such as the Thompson potters in Morgantown, West Virginia (on which topic I highly recommend an article on these potters in the 2011 Ceramics in America).

REALLY overfired bar used on the top of a jug -- the ring in the middle was the top of a jug! Piercy Pottery site. Courtesy, Alexandria Archaeology Museum

Closeup of the melted bar. Piercy Pottery site. Courtesy, Alexandria Archaeology Museum

The (nerdy) humorous thing is to see archaeological evidence that potters who may have been more familiar with one material (i.e. earthenware), may not have been familiar with the other (i.e. stoneware). Which explains why sometimes you read about potters being brought in for their expertise in one material or another. For example, when I was recently at the Alexandria Archaeology Museum, I saw a collection from the Piercy Pottery site. This was primarily an earthenware production site, but there was some evidence of stoneware production as well. I should say that there is speculation that because the amount of stoneware wasters are so low, the attempts at stoneware production were made in the late 18th-century when the site was rented by another potter who went on to make both earthenware and stoneware. Either way, the wasters revealed that at some point their stoneware attempts went horribly wrong! The stoneware separator bars they made are also some of the thickest bars I have seen yet, which is not surprising after seeing their earthenware separator bars (first photo at top). 

On left, bisque stoneware separator bar and fired salted separator bar on right. Piercy Pottery site. Courtesy, Alexandria Archaeology Museum

Their method of stacking the stoneware pottery seems more precarious, too. Typically, one wants to balance the weight of the pieces over another, placing rims, bases, and other points of weight on top of each other.

Bar adhered to base of jar, with indentation showing where the rim of another jar rested during firing. Piercy Pottery site. Courtesy, Alexandria Archaeology Museum

How the base of the jar rested above the rim of the other vessel-- off center! Piercy Pottery site. Courtesy, Alexandria Archaeology Museum

I said that this was humorous because I reflect on these pieces both as a potter and as a scholar. As a potter, I can only imagine the horror on the workers' faces when they opened the kiln and their experiment had gone horribly wrong (been there, done that!). I chuckle sometimes because I think there were a lot of "oh, poop!" moments historically, just like there are in contemporary potters' lives. And as a scholar, I reflect on the attempts of pottery production sites to challenge an import market, a growing population of potteries, and the changes in the uses of utilitarian vessels and forms.
For more information on the Piercy Pottery site, be sure to check out Barbara Magid and Bernard K. Means' article in the 2003 Ceramics in America. You can read the text here, but you miss the beautiful photos!