Saturday, August 28, 2010

From the Ground Up

For the last few months, I've been working on finding and preparing my own clay bodies. Like most things, the price of clay has skyrocketed in the last few years, and knowing that I can throw as much clay as I want without worrying about the price has really freed up my creativity.

Dunedin with its ancient volcanic rock is a good source of plastic, terracotta clays - from weathered basalts up North East Valley to schists around Brighton. Each clay has its own personality, and using local clay gives a pot its own unique character, grounded in space and time. It can be refined, but is also really nice used raw with all its impurities.

Most how-to pottery books give the basics on finding clay. Road cuttings and creek beds are good places to look, sometimes local history and place names can hold clues as to where to start digging. Here I am prospecting in North East Valley, where I found a very nice terracotta:

And here I am digging behind my studio in Brighton, where I found another terracotta, also very good on its own.

Once dug, the clay needs to be tested for plasticity, shrinkage and firing range. A little minigama kiln is perfect for test-firing small amounts - and you can get some sauce dishes and beakers out of it, too. The local clay I've found so far seems to be good around Cone 02.  Here's some terracotta bowls I fired out of the first batch of NEV terracotta, with my minigama:
Minigama kiln and test pots

Processing the clay takes around two or three days. I break it up and dry it in the sun, crush it, sieve it, then put it in buckets covered with water and blunge it with an electric drill. I then pour it into a clay bath to settle, dry it on plaster bats, and  finally put it through a pug mill and into bags. (We're working on putting together a You Tube video which should show the whole thing). It's a messy business but not too hard once you get into a system. Not all that much different than recycling clay.

The next step for me will be to develop some Cone 02 glazes for my clay body, but in the meantime, the terracotta also looks gorgeous on its own.

It's perfect for flower pots and planters, which look great on a windowsill but will only get more beautiful the more they are left outside:

Rustic flowerpots

I also used it to make some amphorae and West African style pots, which I fired to Cone 02 (1120 Celsius) on Thursday:


Opening the gas kiln, after work at NZ Post

Some African-style pots in front of the stack, sitting on the planters, amphorae in the background.

 North East Valley terracotta amphora

Close up showing the coarse natural texture of the clay


tina said...

Hey Dan,

Congratulations on your Blog - it's fantastic! The pottery and scenery images are really beautiful!
Well done!
Will catch up next time I'm down your way.
Best wishes,
Luv Tina

Peter said...

Hi Danny,
Great post! Really useful information about using local clay.