The Search For Wild Clay in Virginia
As soon as I arrived at Cub Creek Foundation in Virgina, I began my search for a good source of wild clay to begin making a body of work with. I had heard that there was wild clay on Cub Creek’s property, and went to collect some of this clay as soon as I could. I had also heard there was a Kyanite mine nearby, and had noticed that the local soil had a rather sandy quality to it.
Red Clay at Cub Creek
White and Ochre Clay at Cub Creek
Upon inspection of the clay on Cub Creek’s property, I found a variety of materials that were not very plastic, contained lots of sand, and seemed to be very refractory in firings. There are three shades of clay on this property; red, white, and ochre. Knowing that I intended to throw, I immediately knew these clays would only work as a single component within the material I wanted to begin experimenting with. Later I discovered a mineralogy breakdown of these materials, and confirmed that the ratios of Silica and Kyanite were very high, translating to a very high maturation temperature in firing.
Line Blend of Ochre and Red Clay from Cub Creek
In my initial tests, I made a line blend of these local clays with themselves to test maturity and vitrification once fired. As I expected, these clays felt very under fired at cone 10 (bisque-like) and did not take ash well, cementing the idea that I needed other materials to have Cub Creek Clay work well as a clay body in my studio practice. Knowing that these materials were not plastic, I needed something extremely plastic to add, as well as something with a lower melting temperature to help the clay mature at cone 10.
The search commenced. I went straight to the Virginia department of energy’s website; specifically their list of minerals and clays in the region. From my experiences with wild clays on the coast of Alabama and education from Zach Sierke’s wild clay workshop, I knew that the most plastic clays were likely to be Kaolins and Shale clays. This line of thought led me to a map of the clays in Virginia.
From this map we can also see a high concentration of materials in Rockingham County, which sits conveniently two hours north of Appomattox, where I am situated. Noticing that this is valley and ridge land, I expected to have good access to cross-sections of exposed mineral deposits.
From here I began to search sources cited on this department of energy webpage, specifically in Shenandoah, Rockingham, Augusta, and Rockbridge counties. Most of these sources consist of older documentation recorded in the early to mid 1900s, meaning that infrastructure has likely grown over some of the sample collection coordinates since these documents were written. I made a list of coordinates from collection sites that had reports of shale clays and kaolins, then cross-referenced those coordinates with google earth’s satellite imaging to see if they were still viable. After this process, I had narrowed my search to fit a few requirements; easy access near roads, public land ownership (National Forest and Bureau of Land Management), and visible deposits in satellite images. This, I hoped, would ensure that I could easily access said materials without carrying heavy buckets over long distances and without having to physically excavate the material from the earth; all while operating on land where it is permissible to do so.
I loaded my shovel and a few buckets into my car, and hit the road. What I found that first day was astonishing, and almost too good to be true.
Mountains of Kaolin
On the border of Augusta and Shenandoah Counties I found immense deposits of kaolins and a whole spectrum of kaolin-shales. I could not believe my eyes. I quickly collected a few buckets of material and headed back to Cub Creek.
Having never had the opportunity to work with such fine materials, I began to process this kaolin in the same way I had always processed wild clay—slaking, sieving, and drying. I found this process to be exceedingly slow and strenuous. On my next attempt, I dry-sieved the powdery kaolin ore and pulled all of the bits of unusable sandstone from the mix. This allowed me to begin mixing clay bodies much easier, as I could weigh the material without concern over water weight.
Inital clay-body mix
In my inital mix, I used:
40% Wild Kaolin
20% OM4 Ball-clay
20% Minspar
20% Silica
This test fired beautifully, shrank 12%, and did not slump at cone 10. I went on to make a 100lb batch to begin making work with.
Pots from my Initial Porcelain-Stoneware Body
After working with this inital body, I felt that the OM4 had a sticky quality that I did not prefer. I substituted the OM4 for XX Sagger in my next mix, and much preferred it.
A Bonsai Pot from my secondary mix
After having the opportunity to get to know this material, I decided to start attempting to increase the amount of wild clay in the mix. Porcelain has a rather thixotropic working quality that I enjoy, but I wanted a clay that felt more like stoneware. I began to replace the commercial ball-clay and silica with the clay on Cub Creek’s land. I did this for several reasons. Commercial material is extremely fine, adding plasticity to a material that is already very plastic by nature. Cub Creek’s white clay already contained lots of silica in the form of sand, a coarser material that would temper the clay, increasing it’s particle size variation and strengthening its working quality. It also contained fine clay similar to a ball-clay like XX sagger or OM4. My new mix contains;
35% Wild Kaolin
35% White Cub Creek clay
20% Minspar
10% Pyrax (to reduce thermal shock in crash cooling, etc.)
I now have a very simple wild clay body containing mostly wild clays. I have always added commercial minspar to wild clays such as these, since they are highly refractory on their own and struggle to reach maturity at cone 10. I have also begun adding pyrax to clays to reduce thermal shock, since most of the firings I participate in involve some degree of crash cooling. Here are some of the soda-fired pots I have made from this clay body:
