 | Productionprocess |  |
Our entirely handpainted decorations always have a white background. That's why we use
a white baking clay. This clay is imported from Germany, the Westerwald and from England,
Cornwall. Our local clay doesn't burn white but red and yellow. We mix the clay with water
to get a liquid clay and we pour this liquid clay into moulds. The moulds are made out of
plaster of Paris which is very porous and it absorbs the water out of the clay. It makes that
the clay dries. The clay dries quicker at the plasterwall as it does in the middle. As a result
of this, a thin claywall forms itself. After half an hour the claywall is already 4 mm thick but
in the middle it's still liquid. At that moment we turn the moulds upside down to pour out the
remaining liquid clay. That's how we make an article hollow. After about four hours the clay is
dry enough to open the moulds and the clay vase can be taken out of the mould.
The edges are trimmed with a knife and the article is smoothed with a wet sponge. The articles
are dried for three days before they are put into an electric heated kiln.
The firing takes 8 hours and the temperature reaches 1040 degrees Centigrade (which is about
1900 degrees Fahrenheit). The cooling down takes about 24 hours.
During the firing, the clay changes into stone which is called biscuit. Directly on this biscuit
we paint our decorations entirely by hand. The painter uses a black paint. After the painting,
the items are glazed with a white glaze. Then the items are fired again in the electric kiln.
During the firing the glaze melts and becomes transparant, the black changes into blue. The
black paint consists of two oxydes: copperoxyde and cobaltoxyde. There is a chemical reaction between the black paint and the glaze and that makes that the black becomes blue.
The other paints, used for the multicoloured Delft do not change colour. These paints intensify
during the firing.