Lab 7: Group D Pottery Data

Group D: Wendy Erickson, Brendan Glenn, Zach McCrary, MJ Fielder-Jellsey, additionally my housemate Astrid Malter and I did the lab activities using the same zoom screen

Location: All lab activity was completed over zoom in separate spaces

Instructor: Kelly Cannole

Within this lab, we attempted to gain an understanding of the differing properties and components of clay pottery. We then sought to use several different pottery techniques to form small pottery vessels using two different clay types.


  • Arb clay (small powder bag): Clay harvested from the Carleton arboretum, dug from below the topsoil layer at least a foot below ground level
  • Refined clay (large powder bag): Typical clay as used by Carleton art students, clay is mixed with other materials that help with the forming and firing processes such as grog and flux
  • Grog (small bag): Sand-like material added to the clay to reduce drying and shrinkage and therefore improve the stability of pottery throughout the firing process
  • Water bowl: Used for adding moisture in bulk to the clay mixtures as well as moisten the edges of clay while working to aid adhesion
  • Improvised marking devices: Found and utilized by students to create patterns on the surface of the partially dried pottery
  • Improvised covering materials: many of us utilized paper, plates, or mats to confine the mess of the project in the absence of an outside workplace
Refined Clay Arb Clay
Warm tan colorDark brown color
No smell Muddy smell
Very fine texture, similar to flourFull of small particulates and organic matter
Easy to add materials to and shape smoothly More difficult to shape and especially to carve given the presence of granular irregularities
Less visible drying process, color of dried pots similar to starting clayVisible gradation in drying process, large color difference in end product


Clay Mixing:

Once we examined the properties of the clay types, we were instructed to separate out half of the arb clay and add an undefined amount of water to the powdered mixture. It became clear that extra powdered clay was a good resource to have given overzealous watering of the first half of the mixture. Several lab group members report continued difficulty in managing liquid levels in the mixture; it seems to have been the most error-prone part of the process. According to Zach, the arb clay mixture:

“quickly got too wet, and instead of only sticking to itself, it began sticking to everything, most particularly my hands”. – Zach

Our instructor provided a useful strategy to test whether our clay contained the correct amount of moisture: form a roughly finger width coiled rope of clay and wrap it completely around your finger. If this results in large breaks, the clay is in need of more moisture; if it is difficult to form a solid coiled rope in the first place, the clay needs more solidity. Even with this strategy, we found that big mistakes could be made in adding too much or little water content to the powdered clay.

The last step to the clay mixing process required the addition of grog to help with the future durability of our potery products. There are two techniques: adding the grog in bulk before mixing the clay with water and adding it gradually after the formation of a hydrated ball of clay. Personally, I prefer the first method of pre-mixing in the grog as it allowed it to be added in bulk quickly to the mixture.

Pinching Technique:

Each student was instructed to create a fist sized ball, punch an indent in the middle, and then push their thumb into the depression to create a rounded shape. This is the core of the pinch pot technique which creates the bottom of the pot. We each then used our thumbs to shape the sides of the pot, attempting to narrow the sides to the ideal width of approximately 1/4 inch. (See Astrid’s left pot for an example of exclusively this technique.)

Coiling Technique:

This technique used coils of the clay to add additional height or width to the pot. First, it is advisable to add a little bit of moisture around the rim of the vessel. Coils are formed by spinning a thin rope of clay between your palms, placing it on the rim, and smoothing out the seams by gathering material from above and below the break. Additional coils could be added to the inside, in order to narrow the pot, or to the outside to expand it.

“The early medieval English people whom we’re primarily focusing on in this part of the class used coil-built pottery, not having the wheel, and so we learned to add coils to the rims of our pinch-pots in order to build up a more elaborate, closed vessel shape”. – Brendan

For my large refined clay pot, I used this set of techniques to first widen and then narrow the shape of the pot. I found that it was a useful technique to score the seam with small incisions of my finger nail after the addition of a coil to make sure that the clay was creating a durable connection.


Each student set their pot out, preferably in the sunlight, to dry over a period of a week until the firing process. It was interesting to see how the arb clay and refined clay reacted differently to this process. The arb clay (as seen above to the far left) seemed to dry with a gradient, the bottom retaining significant moisture after a day of drying. As seen below, after five days of drying the color evened out to a light brown somewhat lighter in tone than the original powder clay. By contrast, the refined clay seemed to dry without visible differences across the surface of the pot. Additionally, it may have dried faster in total but this was difficult to judge scientifically.

Marking / Burnishing:

For my largest pottery dish I attempted several different marking techniques after a period of about 24 hours of drying to firm up the surface of the clay. First, I attempted a stamp-like effect with the cap of a standard sized marker. This tool was able to create an indent in the surface fairly easily an didn’t clog with too much debris. At the top of the pot, I attempted a line around the brim with a scraping technique from a small pencil. I found this process significantly more difficult than the stamping effort, I had to routinely clear the pencil of scrapings and go over the markings I made several times to remove stray bits of clay.

Another student within my group, Zach, is reportedly going to try the process of burnishing the pottery once it dries a sufficient amount. Burnishing is similar to polishing and produces a glaze-like finish on the final product without the use of a glaze. A smooth stone is repeatedly used to smooth the edges of the pot to produce this effect.


There seems to have been significant differences in the ease of this activity among the lab group. For my part, I think that I lucked out in forming the refined clay with a perfect moisture content for shaping. Others were not so lucky and this significantly altered how easy the rest of the shaping process was. Some took the step of resting the clay for a matter of hours or days to dry out the clay enough to enable shaping. I think that with practice and the use of standardized formulas for moisture and grog content in the mixing process this step would be significantly more successful.

It was clear that there are large differences in the quality and workability of the arb clay and the refined clay, especially in our relatively inexperienced hands. The small pebbles in the arb sample were a significant deterrent to forming a fully flexible clay, if found that the pot I produced had a thickness larger than 1/4 inches as a result. It also made attempting to carve into the surface in an even way difficult, I gave up after a few small incisions. My guess is that the arb clay is most similar to what earlier peoples would have worked with. In this case, it was a useful exercise to use this material and experience its difficulties.

An overarching theme of this activity was the forgiveness of clay as a material. Pretty much no matter what mistake you take at the formation stage of pottery, there are ways of correcting and recovering from an excess of materials or error in shaping. Unlike some of our other activities over the course of this term, like cheesemaking or the ritual sacrifice, there is not the overwhelming tension of messing up the process and therefore losing important material investments. This resilience allows experimentation, a plethora of shaping techniques, and flexibility in the timeline of shaping pottery. The next stage of firing will be the place that we see the most uncertainty and pressure in the process.

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