Hi, this is Wayne again with a topic “Primitive Technology: Purifying Clay By Sedimentation and Making Pots”.
Raw clay, The clay is full of rocks and other impurities that may burn away or explode in the kiln Digging a pond to collect the clay Compacting the soil, so it doesn’t contaminate the clay Digging raw clay rocks and roots included. Dumping clay in a pile above the pit Digging a well in the clay pile, Adding water Mixing water, so it becomes muddy. ( Clay particles become suspended in solution, ) Draining the clayey water into collection pit. This was repeated several times the collection pit being topped up as the water level decreased Note. All the rocks left behind in the upper pit.
The lower pit is left to settle. It is now free of rocks and other impurities. The refined clay is taken out of the pit to dry on the ground To source the grog old, broken roof. Tiles were used, Grog is finely crushed up pottery.. It is added to clay to prevent it from cracking while being fired.. The small pieces of ceramic prevent thermal shock in the pottery as the temperature changes., Adding grog to clay and mixing it in.. This will help dry out the saturated clay as well Clay ready for pottery Making round clay disks to form the pottery on.. They have no central rotor to turn on and so are not true pottery wheels.
A layer of ash helps prevent the pot sticking to the discs. Forming the base of the pot note. The disc can be turned instead of the potter moving making it easier to form Making several pots simultaneously, adding layers to some while the others dry is efficient. Use of time.
Coils are added to build up. The pot Measuring is important so as to ensure they all fit into the kiln. Forming the pots on discs allows them to be moved (. It was going to rain here ).
I found it faster to flatten coils into long slabs to add to the pot rather than use round coils Each layer needs to be melded with the one below inside the pot and out Roughly completed pots, Smoothing pots with a flat piece of wood while still moldable. This compresses strengthens and thins the clay wall Burnishing the stiffened, but still damp clay to give it a glossy semi waterproof finish: Burnishing flattens, the clay particles, so that collectively they form one smooth surface. ( note the difference before and after ) A shell can be used. Also to burnish clay Drying out the pots till they are bone dry before firring., Damp pots explode and spall in the kiln due to steam escaping Dry pots, ready to fire, Making a clay sluice as well as pots Scoring the clay to catch the heavier sand.
Sluice ready to fire I’m going to fire some bricks as well.. This will make the firing more worthwhile, making use of otherwise empty space., Putting the pots on top of the bricks where they will be protected from sharp temperature changes.. The pots are upside down to trap. The rising heat inside and bake more fully, The sluice then goes on top Fire by friction, Pushing the lit fire into the ash pit of the kiln first and adding wood here. This slowly heats and further dries the pottery before the proper firing commences Covering the pottery. With broken tiles, to trap the heat in Now adding wood on top of the grate for the proper firing In a short time, the flames come trough. The top of the kiln. The wood is added for 1hr 30 min until the pottery at the top is glowing red hot.
The next day the cool kiln is opened. A ringing noise when struck indicates the pottery is well fired and structurally sound. A hollow sound indicates cracks.
Terracotta xylophone Extra fired bricks always come in handy for later use. Brick stack Water test for the pots. The pot survives the water test and will make a handy bucket for carrying water Testing the sluice The sluice works, but the grooves are a bit deep, catching coarser sand, rather than the finer magnetite I’m after for iron ore. Next time I’ll make shallower grooves, like I did with the first sluice Processing clay is much easier now using the sedimentation method, allowing a higher quality clay to be obtained with less labor Processed clay. .