This blog has been created to share ideas about using clay in the classroom. The author, Debbie Qadri is a ceramic specialist who works in schools. ( amongst other things)
Showing posts with label handbuilding. Show all posts
Showing posts with label handbuilding. Show all posts
Thursday, September 25, 2014
coil building
Coil Building
This page will go over some basic guideines for coil building and give you some ideas about how to use this building technique.
Coiling is the term for building ceramics out of coils or sausage shapes.
You should roll the coil on an absorbant board such as :
I also use a board for rolling and a smaller square board for building on. Because rolling the coils takes up a bit of room.
If you are working with students you can slip and scoring as joining techniques for coil pots. I tend to teach the technique without slip and scoring, using a moist clay. But if students work more slowly or have particularly warm hands, or it is a warm day, or they touch their pot too much, they will most likely have to use slip and scoring because their clay will become too dry to join.
scoring on a coil pot is best done with a thin potters knife.
Slip - can be made by mixing clay and water. It is more easily made by dropping completely dry clay peices into water.
The little jug above has been started off with a pinch pot. If you start with a pinch pot, you will have a rounded base. If you want a flat base for your coil pot, you need to make a slab base. The slab should be rolled out about 1 cm thick and cut to shape.
When joing coils without slip and scoring, I always blend the clay downwards on one side ( such as the inside) and upwards on the other side.
So I place the coils on the pot as a spiral, blending down on the insdie as I go around. When the coil has run out. I blend up on the outside, till I am happy with the shape of the pot.
Then I will add the next coil, continuing in the spiral.
If you work in a spiral it will make it easier to keep the shape of the pot how you want it.
decorative coiling
When you do decorative coiling work, you seal the coils on the inside but not on the outside.
In this method you can see the patterns of the coils.
It is really important to dry the decorative coil pots more slowly to enable the clay to meld.
If you dry the pots quickly they will be more inclined to crack between the coils.
right: open coiled jug with pressed decoration added, using a stamp and a skewer.
The feet were added last.
You can also do decorative coiling very easily in a mould.
Place your coils into the mould in a decorative manner, filling up all gaps with clay and then smooth the surface.
Adding colour to decorative coil projects.
Inlaid slip is also a good method to use, to add colour to the project and to bring out the decoration.
When the pot is hard enough to handle, you paint liquid underglaze or decorating slip into the the gaps between the coils.
You can do this quite roughly and quickly. Then you use a knife or a metal scoop tool to scrape back the slip from the top surface, so it is only left in the cracks. If you prefer a smoother look, you can use a damp sponge to wipe back. I personally prefer the scraping method as the edges have more definition. There is a clear edge between the colour and the natural clay.
You can also paint or sponge oxide into the cracks and wipe this off with a clean well wrung sponge.
below: a tile made in a mould. The back of the tile has been smoothed over so that the coils are well joined.
The two clays are terracotta and white earthenware handbuilding and have a similar shrink rate.
I often use them together in ceramic peices and they fire well. Not all clays can be joined so easily.
The tile has been popped out of the mould while soft so that it could be decorated with little marks. These were made with a skewer - my favourite decorating tool.
This page will go over some basic guideines for coil building and give you some ideas about how to use this building technique.
Coiling is the term for building ceramics out of coils or sausage shapes.
You should roll the coil on an absorbant board such as :
- as the rough side of masonite,
- unsealed mdf,
- particle board,
- cement sheet.
- plywood,
I also use a board for rolling and a smaller square board for building on. Because rolling the coils takes up a bit of room.
If you are working with students you can slip and scoring as joining techniques for coil pots. I tend to teach the technique without slip and scoring, using a moist clay. But if students work more slowly or have particularly warm hands, or it is a warm day, or they touch their pot too much, they will most likely have to use slip and scoring because their clay will become too dry to join.
scoring on a coil pot is best done with a thin potters knife.
Slip - can be made by mixing clay and water. It is more easily made by dropping completely dry clay peices into water.
The little jug above has been started off with a pinch pot. If you start with a pinch pot, you will have a rounded base. If you want a flat base for your coil pot, you need to make a slab base. The slab should be rolled out about 1 cm thick and cut to shape.
When joing coils without slip and scoring, I always blend the clay downwards on one side ( such as the inside) and upwards on the other side.
So I place the coils on the pot as a spiral, blending down on the insdie as I go around. When the coil has run out. I blend up on the outside, till I am happy with the shape of the pot.
Then I will add the next coil, continuing in the spiral.
If you work in a spiral it will make it easier to keep the shape of the pot how you want it.
decorative coiling
When you do decorative coiling work, you seal the coils on the inside but not on the outside.
In this method you can see the patterns of the coils.
It is really important to dry the decorative coil pots more slowly to enable the clay to meld.
If you dry the pots quickly they will be more inclined to crack between the coils.
right: open coiled jug with pressed decoration added, using a stamp and a skewer.
The feet were added last.
You can also do decorative coiling very easily in a mould.
Place your coils into the mould in a decorative manner, filling up all gaps with clay and then smooth the surface.
Adding colour to decorative coil projects.
Inlaid slip is also a good method to use, to add colour to the project and to bring out the decoration.
When the pot is hard enough to handle, you paint liquid underglaze or decorating slip into the the gaps between the coils.
You can do this quite roughly and quickly. Then you use a knife or a metal scoop tool to scrape back the slip from the top surface, so it is only left in the cracks. If you prefer a smoother look, you can use a damp sponge to wipe back. I personally prefer the scraping method as the edges have more definition. There is a clear edge between the colour and the natural clay.
You can also paint or sponge oxide into the cracks and wipe this off with a clean well wrung sponge.
below: a tile made in a mould. The back of the tile has been smoothed over so that the coils are well joined.
The two clays are terracotta and white earthenware handbuilding and have a similar shrink rate.
I often use them together in ceramic peices and they fire well. Not all clays can be joined so easily.
The tile has been popped out of the mould while soft so that it could be decorated with little marks. These were made with a skewer - my favourite decorating tool.
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Freestyle slab method ( good for animals that don't have legs or are stylised so they dont have separate legs. - e.g. chicken fish, bird)
In this method you roll out two slabs about one centimetre thick each. I use terracotta or white earthenware handbuilding clay.
On one slab draw the shape of your animal.
Cut it out using a needle tool or skewer. ( with young children a knitting needle can be used for this, or you can cut it for them)
Use the second slab to make the opposite shape. Lay the first slab (cut to shape) over it and trace it with a skewer. Then cut it out.
you could use precut templates made from cardboard or plastic.
So you have two slabs that represent either side of your animal
Use slip and scoring around the edges of both shapes.
One shape is laid flat, good side down, slip and scoring added around the edges.
Place a small scrunched piece of newspaper in the centre.
Place second slab over top of it and beginjoin them together.
Join them a little all around except for the bottom which must be open. then stand the piece up.
Join all edges nicely and then hold the work carefully in your hands upside down to reinforce the base with a coil.
to
Two pinch Pots
- practice making pinch pots for the first lesson.
- make two pinch pots and jointhem with scoring and slip. Add a coil of soft clay around the outside and blend onto both sides to reinforce the join.
When adding legs etc, make sure that any addition is reinforced with a coil of soft clay around the join, well blended into each part. This will thoroughly join the two parts.
Coiling
Plan carefully for coil built animals.
sketches need to be made of what the animal will look like from all sides and perhaps a floor plan, which can then be used as a template.
draw and cut out template of the bottom of the animal.
Coils should always be a centimetre in diameter. They do not need to be joined with slip and scoring if the clay is soft and is blended to the coil above and below it as you build.
Coils should be added in a spiral, not a doughnut. The coil is blended in as it is added to the pot. Not even sat on top of the pot in a circle and then joined on. this causes wobbles in the pot building.
The artwork needs to be continually compared with the drawing to make sure it is being built to the correct shape.