This relief panel is being made to use as a mirror frame, but it can be used in many ways – to form decorative walls for dishes, cups, plates or in fact, any form you might want to apply it to
You will need:
Plaster clay (clay reserved for plasterwork only)
Receptacle for mixing the plaster
Scales – jug – newspaper and bowl
A cutting mat
Before you begin:
Mirror tiles can be bought from most DIY stores and are available in several sizes.
When deciding which size to buy, bear in mind the dimensions of your kiln because the frame will be larger than the actual mirror when finished. You may want to add up to 10cm to the size of the mirror, which is substantial if the mirror is large in the first place.
Note: if you make your relief mould to the maximum size that will fit in your kiln, you can make smaller frames from the same panel.
BE AWARE that this is a time-consuming project which requires close attention to detail to make a successful mould. You can, of course, simplify your design but it is still vitally important to ensure the model for the mould has no undercuts, and working to this end takes time!
The model is made in two stages – a sprig mould first to save having to make the repeating parts separately, then the panel itself.
If you have mirrors in more than one size, make your panel to fit the largest size – this will allow you to make smaller versions when required.
Begin by measuring your mirror.
Now calculate the size of the panel you need to make, bearing in mind that the mirror needs to be inset.
So, for example – this mirror is 30cm square. A 7cm panel will overlap the mirror and contain it by 3.5cm (which will reduce the viewing size, so bear this in mind), and extend out from the edge of the mirror by 3.5cm making the total dimensions 37cm square.
Working out a design on paper is always a good starting point for any project because you can iron out potential problems before you have committed to clay. Therefore, this first exercise is for planning – it will help you calculate the ultimate size of the frame and work out the design. Note, you do not have to copy the design shown here, but the layout will help you understand spatial considerations. This design forms a loose repeat.
Begin by cutting out a strip of card to the length you have worked out.
Draw a line 1cm deep along each side of the length and at each end.
Divide the internal space into equally sized sections then draw a circle (or shape of choice) in each area. Use a compass or something appropriately sized to draw around.
Measure and mark a distance of 7cm from the end of the template then draw a dotted line
from this point to the opposite corner. This is the angle the corners will be cut to when making a frame.
Repeat at the opposite end of the template.
Make a second template in the same way.
When you put the templates together at right angles, you can see how
the ends will fit once cut along the dotted line and get a clearer idea of the finished size.
Draw a circle on an old tile or small non-absorbent board using
a marker pen. Make it the same size as those drawn on the template.
Roll a thin coil of clay, about 5mm thick, then pinch it gently along its length to triangulate it.
Arrange the coil in small lengths inside the circle until the space is completely filled.
There must be no undercuts in the coil arrangement, so carefully fettle around the coils with
a wooden or plastic tool until the pattern is neat and the surface smooth.
This sprig now forms the basis of a repeating pattern for the panel.
Roll a thick slab of clay and cut it into strips about 3cm deep to form
a cottle around the sprig. You can position the cottle as a circle around
the sprig or build the walls as a square. Leave about 1cm around the shape
when you position the cottle, then secure it in place with a coil of soft clay.
Make up a very small amount of plaster – 290ml (¼ pint) of water
and 170g (6oz) of dry plaster should be more than enough.
Once mixed, cast the sprig.
When the plaster has set (gone off), remove the clay cottle
then surform the sharp edges to round them off.
Lift the mould off the tile and surform the side and top edges.
Carefully remove the clay from the mould and clean it up with a damp cloth to remove all clay residue.
Allow the mould to dry out somewhere warm.
Using your template for reference, transfer the design to the surface of a non-absorbent board, using a marker pen.
Press a small slab of clay into the sprig mould, then carefully tear off the excess around the side.
Level the top by drawing the side of a batten over the surface – be careful you don’t drag the clay out of the mould as you do this. Work from the centre to the sides.
Lift the sprig out of the mould with a wad of soft clay.
Position the sprig on one of the circles on your board, then make enough sprigs to fill the rest. You can align the sprigs in one direction for an exact repeat or offset the angles of each one to make the design more visually lively.
Roll another thin, 5mm thick coil of clay and pinch it to triangulate it as you did earlier.
Fill in the spaces between each sprig with short lengths of the coil – repeating the arrangement as exactly as possible in every space. Cut the coil to fit to the inner line, on each side of the sprigs.
Blend the extra coil detail in with a wooden tool to neaten up and ensure there are no undercuts to trap plaster when you cast the panel. When finished, the extra coils should look like an integral part of the design.
At each end of the panel, work around the last sprig with coils until the space is filled up to the lines on all sides.
The panel with all the spaces filled in will take a considerable amount of time to complete. If you can’t do it all in one go, cover it over with a plastic sheet to prevent it from drying out before you can work on it again.
Roll out a length of slab 5mm thick, long enough to fit along the length of the panel.
Cut the slab into two 10mm-wide strips and butt one up to each side of the decorative panel using a batten to ease them into position.
Make sure there are no gaps or undercuts between the side strips and decorative area. Neaten up as before with a wooden tool until the strips look a seamless part of the panel and you have removed all possible undercuts.
Cut off the excess strip at each end with a metal scraper or knife, as shown, level with the end of the decorative centre.
Roll out a thick slab of clay to make a cottle around the panel. Cut the slab into two 3-4cm width strips.
Place a batten each side of the panel then butt the cottle wall up to it as shown.
Reinforce the cottle with a coil of soft clay to prevent plaster seepage when casting.
Cut the side walls of the cottle in line with the end of the panel.
Butt the cottle ends right up to the end of the panel and secure them in place as before.
The panel is now ready to cast in plaster.
Mix a measure of plaster to fill your cottle – the amount will depend on the size of your panel so scale up or down from the basic ratio of 680g (1 ½lb) of plaster to 570ml (1 pint) of water.
Mix the plaster in the water until lump-free, and it begins to thicken, then pour it over the panel until the cottle is filled.
Once the plaster has gone off (heated up and cooled down again – set and hardened) remove the clay wall and surform the sharp edges of the plaster to round them off.
Dispose of the plaster shavings carefully, to avoid contaminating your clay.
Turn the mould over and surform the upper, outer edges.
Lift the clay out of the mould then clean up the surface with a damp cloth, to remove as much clay residue as possible.
Put the mould somewhere warm to dry out thoroughly before use.
This project first appeared in issue 32
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