Primitive Technology: Purifying Clay By Sedimentation and Making Pots
Clay is full of rocks and other impurities that can burn or explode in the kiln Dig a pond to collect the
clay Compact the soil so it does not contaminate the
clay Dig up raw
clay, including rocks and roots Dump
clay on top of the pit Dig a pit in the
clay heap Add water Mix the water to make it muddy (
clay particles are suspended in the solution) Drain the
clayey water in the collection pit This was repeated several times, and the collection pit was backfilled to the lowered water level Note all remaining rocks in the upper pit Lower pit is allowed to settle Now free of rocks and other impurities Refined
clay is removed from the pit to dry on the ground To obtain grog, old broken tiles were used Grog is finely ground down to ceramic.
It is added to the
clay to prevent it from cracking while it is being fired. The small pieces of ceramic prevent thermal shock in the ceramic as the temperature changes. Add grog to the
clay and mix it. This will also help dry out the saturated
Clay ready for pottery Make round discs of
clay to form the pottery. They do not have a central rotor to turn and are therefore not true potter's wheels. A layer of ash helps prevent the pot from sticking to the discs. When forming the base of the pot, keep in mind that the disc can be rotated instead of the potter moving,
making shaping easier.
pots simultaneously, layering some while the others dry is an efficient use of time. Coils are added to build the pot. Measurement is important to make sure they all fit in the oven. Shaping the
pots into disks allows them to move (it was going to rain here). I found that it was faster to flatten the coils into long slabs to add to the pot instead of using round coils. Each layer should merge with the one below it, inside and outside the pot.
clay hardened but still wet to give it a glossy, semi waterproof finish. Burnishing flattens the
clay particles so that together they form a smooth surface (note the difference before and after) A shell can also be used to polish the
clay. they are completely dry before firing.
pots burst and splinter in the oven from escaping steam. The dry
pots are ready to be fired.
Making a gate out of
clay, as well as the pans. Scoring the
clay to trap the heavier sand. This will make the shot more worthwhile, taking advantage of the space that would otherwise be empty. Put the
pots on top of the bricks where they will be protected from sudden changes in temperature. The
pots are upside down to trap the rising heat inside and bake more completely The damper then goes up Friction fire Push the burning fire into the kiln ash pit first and add wood here This slowly heats and further dries the pottery before proper cooking begins Covering ceramic with broken tiles to trap heat Now adding wood on top of grate for proper cooking Soon flames pass through top of kiln Wood is added over 1 hour and 30 minutes until the pottery on top glows red hot The next day, the cold kiln is opened A ringing sound when struck indicates that the pottery is well fired and structurally sound, a hollow sound indicates cracks Terracotta Xylophone The fired bricks Additional ones are always handy for later use Pile of bricks Water test for
pots Pot survives water test and it will make a useful bucket for carrying water Gate test Gate works but grooves are a bit deep and trap coarser sand instead of the finer lodestone I look for for iron ore Next time I'll go shallower like I did with the first gate Processing
clay is now much easier using the
sedimentation method, resulting in a higher quality
clay with less work Processed