Project 8: Fun with soils
Using soil does not have to be all hard work and no fun. The more we know
about soil, the more we can enjoy it.
SIGNPOSTS IN THE SOIL
Soils often containa record of what happens in places. All soils originate
from rocks somewhere, and will one day be reconstituted into sedimentary
rocks beneath the oceans, uplifted, exposed and weathered down into soilsagain.
This is a continuous cycle and in this sense soils can never be indefinitely
conserved, only used as much as possible during the process.
- Examine your soil.
Where does it come from?
Are the parent rocks nearby?
Are there signs that this soil was transported to where it is today
by wind or by water?
Where is the soil moving to?
What will happen to it eventually?
- Who lives in the soil?
Are there any castings?
Are there any mounds or tunnels?
Are there any termite nests?
Are there any holes?
- Who lives on the soil?
Are there any game paths or rodent runs?
Are there any tracks?
Look for them on muddy clay soils around the waters edge, along paths,
on beaches, around camp sites, in the shade of trees, under bushes,
near kills, in ditches, near droppings.
Make plaster castes, sketches or take photographs of the tracks and
find our what animal or bird makes them.
- Find tracks and follow them as far as you can.
They are usually easier to follow in the early morning and late afternoon
Learn to tell the difference between - front and back feet, walking,
running, jumping, digging, predators and prey.
If you lose a track, fix a stick at the last point and circle around
it until you pick it up again. If you can't find it, the animal may
be hiding within the circle.
- Learn to tell the age of tracks under different conditions.
On sand and clay, on a windy beach, before and after rain.
Learn to identify droppings by their size, shape and age.
[See Signs of the Wild: Clive Walker Natural History Publications.
- Prepare a damp sand pit and make plaster casting of human feet
Use tracks of different size people moving at different speeds.
Know the difference between men and women, tall and short, limping and
walking, carrying, running.
- Examine soil for artifacts.
Rock knives and scrapers.
Broken bones and shells.
Beads and seeds.
Glass, plastics, broken china.
Pottery and old bricks.
Bottle tops, cans, nails, wire, bullet cartridges.
Let every piece tell its story.
Where soils has been infiltrated by other minerals eg iron they take
on a rich variety of colours. This provides a natural palette for the
Make a soil bottle by collecting a variety of coloured soils and
pouring them carefully into an empty bottle to create patterns against
the inside of the glass.
Fill the bottle to the top and seal it carefully. Any space left inside
the bottle allows movement which in time results in the destruction of
Make a stiff starch and allow it to cool. Place a teaspoon of starch
into each of the empty pockets in an old egg box. Collect a variety of
coloured soils and mix with starch as a binding agent. Use these colours
to finger-paint on paper or chew a twig end into a tiny brush and paint
the colours on to paper. Charcoal makes a useful black pigment.
BRING CLAY TO LIFE
Soil is the basis of pottery, it can be learnt without any expense at all
and form the basis of a craft or career which can be further developed throughout
life. The creative nature of clay as a medium which can be fired into permanence
has immense utility and satisfaction. Only the most basic skills will be
covered here and those interested are advised to read further or seek the
help of a local potter. Every potter has to learn by experimentation and
if the only investment is your labour then the occasional flop doesn't matter
and becomes a learning experience.
GETTING YOUR CLAY
- Clays occur naturally in most places, in farm dams, road cutting
and sites where foundations are being excavated. You need to collect
a sticky or plastic clay. Apply the ring test [Project
1] to your sample before collecting.
You should try to collect a sample midway between a short and a fat
clay. Preferably one that forms tiny shallow crack when worked into
- Collect a moist sample in a polythene bag and bucket from below the
surface to avoid contamination. Store your clay in a plastic bucket
with an air tight lid to prevent drying out.
PREPARING YOUR CLAY
- Clay needs to be free of impurities and flexible enough
to model. If your clay was collected dry [as from the cracked bottom
of an empty farm dam] it should be pulverised into tiny bits in a bucket
and sufficient water added to cover the material. After a week of soaking
the remaining lumps are squeezed out of the slip by hand.
- Pour off the excess water.
Transfer the slip to a plaster of paris bat [ dry block of plaster]
which will absorb the excess water. Work [ called wedging] the clay
into large workable lumps kneading out the air bubbles. If the clay
is still too wet allow further air drying time and rewedge. When it
ready for use wrap the wedges of clay in plastic and store them in the
air tight bucket.
MODELLING YOUR CLAY
- If the clay is to worked into thick forms [models]. It needs
to be opened by adding white sand or crushed pottery fragments [grog]
to the clay. This is needed to enable dangerous moisture to escape more
readily from the thicker portions before firing. If the clay is to be
worked into thin hollow forms [pottery] then an opener is not needed.
- There are basically three alternative starting points...
A great variety of form and texture is obtained by beating the soft
clay with wooden paddles, impressing designs into the clay, rolling
it on textured materials, such as bark or old wood, binding it in grasses
or hessian, scratching it and combining clays of different colours together
Once the form is ready the clay is allowed to dry out completely
at room temperature. It becomes harder and lighter in colour as it changes
to biscuit-ware. At this stage the pot will dissolve away if put into
water. Once it is almost dry, it is possible to burnish or polish the
outside of the dry clay using the back of a spoon or small river smoothed
stone. The pot can also be decorated by scratching or carving out grooves
- The ball of clay into which a thumb is pressed to create a hollow
vessel called a pinch pot.
- A rolled out slab of clay which is cut with a knife and stuck together
with slip along its edges before being smoothed together - this is
- A rolled sausage which is coiled into a pot and the coils smoothed
FIRING YOUR CLAY
Not only is this an entertaining and useful skill to learn. The products
can be sold as pots in which your own plants and succulents from your own
nursery can be marketed as part of a fund raising venture.
- No clay can be fired until completely air dried. The initial
firing process must be slow and steady with no sudden changes of temperature.
The pots must be slowly heated to 100 degrees centigrade to expel moisture
slowly. Fast firing will burst any clay objects. Clay changes into pottery
at 500 to 600 degrees centigrade.
- A simple sawdust fired kiln can be made with twenty bricks. Lay two
rows of bricks loosely in an open square 2 bricks long by two bricks
wide. Pack the pots to be fired in sawdust on all sides. Cover them
with sawdust. Insert a twist of paper in the top. Light the paper and
cover the open top with a metal dustpan lid. The fire should burn very
slowly all day and twenty four hours later it should be possible to
remove the cooled pottery. These pots will all be permanently black.
- If you want your pottery to have a more natural colour you will have
to protect the pottery from the firing fuel. This kiln design is a mixture
of the traditional Roman and Japanese wood burning kiln. The kiln is
fired through a fire box constructed out of a small half drum insulated
with a thick layer of clay. Flames draw through the kiln chamber. The
fire should be kept burning throughout the day, it taking about 20 hours
to fire and cool the kiln.