SKILL SCHOOL
PROJECT
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OYA/OLLA
What is an oya, you might well be asking? Well, it’s a terracotta vessel that’s buried in the ground to water the garden naturally. Not only does their use dramatically reduce water waste but also watering time. So, buried in the ground next to your courgettes, you’re bound to get a bumper crop with very little fuss!
Before you begin:
We are using a plaster mould here to make the body of the oya. We’ve used a globe-shaped mould, but you could use any symmetrical shape that will allow for two halves to be joined together – it is simply a receptacle for water, so shape really is irrelevant. It won’t be seen because it will be buried up to its neck underground. You can find instructions for making a half globe shape by visiting claycraft.co.uk/ how-to/oya It should be noted that these vessels can be made in any size – including miniature versions to keep your houseplants watered.
You will need:
■ Red earthenware clay ■ Plaster mould ■ Rolling pin, roller guides, plastic sheet ■ Small texturing tool. See the wonderful range MKM tools has to offer – you will want them all! ■ Foam blocks to support the shape in construction and drying
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DIFFICULTY DIFFICULTY RATING RATING ★ ★★ ★★★ ★★★ ★
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1 Have your mould close at hand, ready for use. Make sure it is clean and dust-free.
Cut a semi-circle out of the slab, which is large enough to fill half of the mould.
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2 Prepare a block of clay large enough to fit inside the mould once rolled – you’ll have to estimate the size according to your mould. Working on the sheet of plastic, reduce the bulk of the clay by beating it with the side of your rolling pin. Work in measured, even strokes from one side of the clay to the other, to avoid making deep grooves in the surface. Roll out the clay between your roller guides. You will find that periodically turning the slab will make rolling much easier and give you more control to achieve the approximate shape you need. Once rolled out, smooth over the surface of the slab with a rib to compact the clay.
Gently ease the slab section into the mould using a barely damp sponge to avoid marking the clay with your fingers.
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Cut out a second semi-circle and place it in the mould so that it overlaps the first half by a couple of centimetres – again using the sponge to ease it into place. 38 ClayCraft Issue 49
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Blend the overlapping edges together thoroughly with
your thumb to ensure the seal has not trapped air between the layers.
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Cut away the bulk of excess clay above the rim of the mould, making sure the knife doesn’t come into contact with the plaster.
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Work over the interior surface of the join with a rib,
removing excess clay as required until the walls are evenly thick.
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Now remove the remainder of the clay at the rim with the side of a batten resting on the mould. Work in small steps, drawing the batten sideways and backwards to remove small sections at a time until the rim is level.
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When the clay has firmed enough for the shape to hold, turn it out of the mould onto a board.
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Reinforce the overlap join on the outside of the shape with a coil of soft clay. Carefully press the coil across the surface into the join with your thumb. Issue 49 ClayCraft
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12 Work over the reinforcement with a rib, removing any excess clay where required, for a neat finish.
Sit one half of the globe on a foam block with a hole cut out at the centre to support it, then score the rim with a serrated kidney. Repeat the process for the second half.
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13 Work over the reinforced area again with a soft kidney until all evidence of the join is eliminated.
14 Make the second half of the globe in exactly the same way. 40 ClayCraft Issue 49
Apply slip to the scored rims, then fit the two halves together carefully.
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Reinforce the join with another coil of soft clay. Blend the coil in well using your thumb or finger, then smooth over the area with a rib, again removing any excess clay for a neat finish.
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The shape and finish of the oya don’t really matter because, after all, it will be buried underground. However, for the personal satisfaction of knowing you have made something to the best of your ability, it is worth aiming for as good a surface finish as possible. So, for example, if the shape is a little distorted and you really would like it to be round, try paddling the surface with a wooden spatula to improve it. If you would prefer the globe to have a base to stand on (this makes firing much easier if you’re nervous about placing unusually shaped items in the kiln), simply tap it on the work surface a couple of times to flatten the underside until it will support itself.
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Look for a circular cutter that’s large enough to get your hand through. Place the cutter on the top surface of the globe and score the outline with a pin.
We don’t often say this, but you can change tools if you think you have one that is more suited to the job at hand. We all have our favourites, and every maker will use several types to form an object. Bearing this in mind then, feel free to change the rib for a kidney to achieve a better finish. Issue 49 ClayCraft
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Roll a thick log of clay about 12cm long, then gently push a length of 10mm dowel through the centre and out the opposite end.
Carefully cut out the circle with a sharp knife and lift it off the globe.
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Holding the dowel at each end, roll the log on the work surface to enlarge the hole at the centre. Continue until you are just able to get your fingers inside the tube.
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22 This is where it is important to be able to get your hand inside the globe. Reinforce the join on the inside with another coil of soft clay. Blend it in well, then remove the excess as much as possible, using a rib. 42 ClayCraft Issue 49
With the tube sitting on a whirler, now begin to pinch the wall to extend the size of the tube. Begin at the midpoint and pinch outward and upward in small rhythmical movements to ensure the wall is an even thickness.
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Turn the tube over and pinch the second half in the same way until it is level with the lower half. The wall should be even throughout, and vertical when finished.
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Now refine the outer surface of the tube using a metal palette rib to ensure it is vertical. Remove clay as required for a smooth surface finish.
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Test the size of the tube on the globe to make sure it is wide enough to fit the opening.
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Score around the opening of the globe, then the rim of the neck. Apply slip to both surfaces.
Return the tube to the whirler, then turning it slowly while holding a knife rigid in your hand, carefully cut the rim level.
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NOTE: - this step isn’t shown, but if you’re unhappy with the size and shape of the neck, you can change it by cutting out four V-shaped sections from the rim (opposite to one another) then joining them back together by overlapping the cuts and blending the clay together thoroughly. This is really only possible if the clay is still relatively malleable, but you can use slip for extra security if you feel it is needed. Blend over the cut joins and the join at the shoulder with a long throwing rib to fully seal them together.
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Work around the join with the round end of a rib until smooth and tidy. 44 ClayCraft Issue 49
Similarly, if you feel the neck wall is too thick, you can pare it back with a surform until correct. Once you have removed the required amount of clay, smooth over the surface with a rib or kidney to remove the marks left behind by the surform.
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The basic form is now complete, and all that remains to do is make a lid for it to prevent the water from evaporating too quickly when the oya is in use.
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Cut the rim of the tube level as you did the neck, then quickly check that the size is correct again and has not been distorted in the cutting.
Form another short log-shaped coil about 3cm long and push the dowel through the centre as you did earlier. Roll the log to open out the centre until you can get your fingers inside.
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Place the tube on a whirler and pinch the shape until wide enough to fit inside the neck of the oya with a little wiggle room.
Working on the plastic sheet and using 10mm roller guides, roll a small slab of clay. Issue 49 ClayCraft
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40 Now using your chosen texturing tool, impress the surface of the slab. This example uses an MKM roller HR 052 – Dragonfly Party design – very apt for the garden.
Cut out the lid from the textured slab, carefully choosing the best area to cut it from.
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Turn the lid upside down and centre the tube on the surface. Mark the position with a pin.
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Measure the size of the lid you will need to cover the top of the oya. Luckily, the cookie-cutter shown was just the right size, but you could make a card template if you don’t have a cutter in a suitable size.
TIP
A multi-sized selection of cookie cutters is really invaluable in pottery. They are inexpensive to buy, so well worth investing in a set – you’ll wonder how you managed without them!
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Score the rim of the tube and marked position on the lid, then apply slip to both surfaces and secure the two together.
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A NOTE ABOUT FIRING: Because this oya has been made as a globe, it doesn’t have a base to sit on in the kiln. You can resolve the issue of keeping it upright by standing it on a suitably sized star pin or support it around the base with kiln props – either method will work. Alternatively – make the oya with a base – it will work the same way!
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Neaten around the outside edge of the join with a wooden tool to remove excess slip, then reinforce the inside of the join with a coil of soft clay. Blend the coil in seamlessly with a wooden tool.
46 Check the fit of the lid in the vessel – it should sit neatly on the rim of the oya with a little wiggle room to allow for shrinkage in firing. Allow the vessel to dry with the lid in place, then bisque fire as usual.
Once bisque fired, a good way of keeping the oya upright until ready to use in the garden is to sit it in a bucket, as shown.
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The great thing about an oya is that it only needs to be bisque fired. When low fired, the porosity of the clay is the key working element of this vessel – allowing water to seep through the pores slowly to keep the ground moist. Issue 49 ClayCraft
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