One of the most common questions I get is ‘Surely wheel-thrown pottery is more exclusive than pottery made in a mould?’.  It’s a very good question and in this article, I’ll try to explain the individual craftsmanship that goes into each of my baubles.

Firstly, one of the main advantages of using a mould is that I can create eggshell-thin and therefore light baubles.  This would not be possible if they were wheel thrown.  You will see that I describe them as ‘hand-crafted’.  It is not just the bauble that’s hand-crafted, it’s also the mould.  I won’t go into the process of making the mould here; you’ll find that in another blog, but I will explain why the baubles are legitimately described as ‘hand-crafted’.

So, starting with the mould I use, here it is.  It consists of five separate pieces: base, two sections for the top of the round part and the neck and two sections for a cone which acts as a pedestal for the glaze firing stage.  That is only necessary for because of my crystalline glaze process.  More of that later.

You can see small indentations and matching lumps in the different sections.  These are designed to make sure that the mould locks tightly together when the slip is poured in.  The mould is assembled one piece at a time and the various parts are held together using a very tight elastic band made from bicycle inner tube.

Once assembled, the slip is poured in.  This needs to be at the right consistency.  The mould is filled right to the top – as full as possible without spilling over.  I use a small container for ease of pouring.

Next, I wait for a few minutes and watch the top where I’ve poured the slip in.  The plaster of the mould starts to draw water from the slip where the two meet, causing the slip to set around the edges.  I am watching for the thickness of the set slip at the top and also the extent to which the level of the slip is falling.  By using my experience, this enables me to judge when the bauble is the thickness I want: thick enough not to break, but thin enough to be light.

I then invert the mould back over my pot of slip and allow the excess to drain back into it, checking that the slip is flowing freely and has not stuck in the neck of the bauble.  Gentle shaking can help, but anything vigorous can cause the bauble to collapse inwards.  When I’m satisfied that the excess slip is out, I place the inverted mould on a rack over a bowl to allow any further drips to run out.  At this stage, it needs to be left for around four hours to dry.

The bauble needs to be removed from the mould very carefully.  If any of the slip has stuck to the sides, it can pull the bauble apart.  The bauble needs to be handled carefully and put to one side to dry off a little, for up to 24 hours, depending on the temperature and humidity.  It is very soft at this stage and even slightly too much pressure can cause a dent.

Once it has dried so that it is rigid but still slightly soft, the excess clay left by the edges of the mould needs to be carefully removed,  This is always slightly nerve-wracking.  If the shell is too thin or slightly uneven, a hole can appear and the bauble is ruined.  I use a special wire turning tool to do this. This removes the worst of the excess but leaves dents and ridges.  Before I can deal with those, I need the clay to dry a little more

Once I’m happy that the clay has dried sufficiently, the next step is to remove the ridges that have been left by the paring and other small indentations and bumps.  I do this by gently sponging the surface.  This results in an almost smooth surface, but the wet sponge dampens and softens the clay, causing another opportunity for dents and holes to be made.  Once I am satisfied with the surface, the bauble is left to dry again.

For the final part of this stage of the process, the porcelain must have dried thoroughly and will have taken on its characteristic white colour.  Using very fine sandpaper, I gently sand the surface smooth.  There is no danger of making indentations at this stage, but the clay is not very brittle and anything but the most gentle pressure will cause it to break.  Additionally, there is still the possibility of removing too much of the already eggshell thin surface.

Once I have made enough baubles and pots to fill my kiln, they are ready for their first firing.  This is known as the bisque firing.  It is a lower temperature than a glaze firing, but hardens the clay to a point where it is no longer so brittle.  It takes around 36 hours for the kiln to fire and cool so that the contents can be removed and the next stage begun.

Some of my baubles will now go through an interim process.  Certain colours are achieved by glazing over a coloured slip.  There are several ways of doing this, but my process involves using a refractory slip on bisqued baubles.  I make my slip from a set combination of several chemicals, with different colourants added, depending on the colour I want to achieve.  To get a smooth, even coating, I apply the slip using a glaze sprayer.  Once dry, the baubles are returned to the kiln to be re-fired at a slightly higher temperature to set the slip.

The next step is where the magic happens.  Unlike conventional glazes, crystalline glazes are applied thickly, with more of the glaze at the top.  There are many, many different recipes which are developed by each crystalline ceramicist through a careful programme of testing both the recipe and the firing schedule.  The glaze firing is where the little extra cone comes in.  Because crystalline glaze is so runny, the cone acts as a pedestal which sits on a dish to prevent the glaze from sticking the bauble to the shelf.

Now for finishing. The pedestal needs to be separated from the bauble, which is done using a tile cutter.  A diamond grinding disc is then used to ensure a smooth, even end.  Lastly, the bauble cap is fitted to the top and voila! A completed bauble.