Ash Glaze

Left to right: fireplace wood ashes, screen made from bucket rim and lid to screen ash and clay, clay from creek on site.

         While waiting for the pyrometric cones to come in the mail, I decided to make use of the fireplace full of high alkali hickory ash by trying to mix up some ash glaze. 

            I dug some gray/yellow clay from the creek on the property and also some high-iron red clay from among the roots of an toppled oak near the kiln. I made a sieve from window screen and the rim and lid of a 5-gallon bucket. Next, I went about sifting the charcoal and debris from the ashes and cleaning the clays. There wasn’t time to dry out the clay but I slaked it, screened it, and tried to guess at the dry weight so I could make something like a 50/50 ash and clay mixture. In the end, both came out pretty rough- no matter how much I stirred, they still would have benefited from a finer screen. I have since gotten a fine screen (100 mesh) and have been able to mix more ash glaze at a consistency that won't clog a spray bottle.  As it was, I dipped some pieces in the ash-slip and brushed it on others. This is all just a first experiment so plenty to learn!

Bug 'pottery'! (clay-lined insect tunnels from inside the firewood that was burned and fired along with the pots)

Screened ashes- still pretty coarse...

But this is the stuff that really shouldn't be in the glaze! Charcoal, twigs, nutshells... you name it.

         

Kitchen Potting: Out of the Kitchen and Into the Fire

           The holidays found me down in North Carolina, where I left the old electric kiln I picked up off of Craigslist. Finally some time to tackle the electric to gas conversion! I brought along a few boxes of dried pots packed in newspapers for a test firing.

           Well, I was unable to make it to the store to get kiln-building supplies for a few days, so I impatiently stashed a batch of pots under the grate in the house fireplace and started firing with wood. The pots were all at least a few months dry and the hickory fire provided a fairly gradual warmup. 

 

 

          I kept adding a log or two every half hour and raking the embers around the pots till they were nested in about 6 inches of ash and coals. After five hours, I let the fire die down and the next morning, I pulled out a couple bisqued pieces and a number of not-so-hard examples (those that sat around the outside edges). I rotated the latter to the inside and went ahead and fired again, adding a few extra pots, with about the same results. The center area (ca. 10 by 6 inches) under the grate made it to bisque temperatures but fell off sharply on all sides- pretty much what you’d expect.

My first 'firing'!

Second Batch

Traveling marmot Ferdinand unpacking the fireplace kiln- three or four different clay bodies here.

Wild Clay

Processing some freshly-dug Virginia clay

 

Work of late has been limited to surveying large parcels of land with hardly an artifact in sight. The monotony is broken, along with the skin, by thorny greenbriar and whip-like woody brush. Also, there has been the chance to gather and try some raw clay.

The gray clay comes out of the ground relatively plastic and willing to be rolled into snakes over a foot long. The orange-red material would do likewise, were it not choked with quartz sand. In fact, I found both to be composed of 10-20% clear quartz together with the usual roots and debris.

Having brought samples home, I sliced each batch into 1/2" slabs. Leaving the plastic bags of clay in the freezer overnight, I tossed each color in its own bucket of hot water in the morning and stirred till they became a slurry. Next, I passed them through a sieve made from window screen, the top of a 5-gallon plastic bucket, and  the edge of the bucket lid. The liquid clay was collected in another container to settle out while the sand was discarded. Both the gray and red clay held the same clear quartz, but the size of the grains in the gray must have been larger. With just this relatively coarse screening, the gray was rendered into a very fine slip, which took a long while to settle out.

The red clay was settled out in a day, at which point I poured off the clear water and poured the slurry into an old t-shirt before mounding it on top of a thick plaster bat to dry to a knead-able consistency. The resulting clay is very sticky but quite plastic. It is not, however, fond of being thrown to too thin a cross-section and tends to crack. A few attempts at thin-walled cups (1/4- 1/8") split at the rims. The teapot below was a test of the material in its pure state. The handle was turned on the wheel as the clay would not be pulled longer than 4 inches.  The addition of another clay body will probably go  long way to solving the cracking problem.

Still a bit stubborn (lid cracked before I could get a pic) but not bad for having been a foot deep in a field four days earlier. The sweetgum ball seemed an appropriate finial and I may make a poison ivy sprig mold for the handle terminii.