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Lustre and precious metals
(I)
A metallic luster effect is quite often obtained in the course of firing
glazes with varying oxide content. However a real lustre is only achieved by
following particular technique and firing procedures, using specially
prepared metallic salt. Traditionally lustres are the salts of copper and
silver, used singly or together in China clay or Ochre. The mixture is used
to decorate ware which has already been glazed and fired with a soft tin
glaze. Firing is must successful in a wood-fired kiln with a short period of
reduction. The maximum temperature for the firing 660oC (1220oF), when cool
the ochre or China is burned off, using pumice powder and a pad of sheep’s
wool to reveal the areas of luster, those potters who are prepared to
develop their own lustres and firing techniques are few in number, but once
they master the technique, it may become a major aspect of their production.
For those interested in using lushes, several manufactures have produced a
wide range of commercial lustres which can be fired at low temperatures.
Slip trailed ceramics
Slip trailing is a long established decorative tradition in several European
countries and remains one of the primary ways in which the surface of a pot
can be enriched. In the lik, for instance medieval slipware is one of the
highlights of the national heritage, its spontaneity and robustness
reflecting the rugged vitality of rural life, such attributes, plus a sense
of humour are also seen in the more illustrative work of the toft brothers
and others of the seventeenth century.
Burnishing a scratching slip
The appeal of this technique, which owes a great deal to non-European
tradition, is in the inexpensive simplicity of the materials required and
the minimum of equipment needed to achieve its effect. Despite the basic
nature of the technique, riches of decoration and design can be achieved. In
these examples, a slip-brushed leather-hard pot can be burnished with the
back of a metal spoon.
Laminated Bowls
Laminated bowls can be created from coils of clay triangles and stripes,
each of a different colour created with body stains and oxides. These are
built up inside the biscuitfied bowls. These can then be fired into 12 14 hr
firing cycle as follows.
1. The building starts with the rolling out of a thin, even clay sausage
with the fingers.
2. A second piece of coloured clay is rolled out in the shape of a long leaf
with a rolling pin.
3. The sausage is placed on the leaf and slip applied with a sable brush.
Sable should be used at is important that no hairs are left on the day, as
these would drag when this is cut.
4. The edges of the leaf are trimmed and the leaf rolled around the white
clay sausage. This process can be repeated layer upon layer.
5. The rod is then cut into thin slices, using a razor blade, the thickness
of the slice being determined by the desired thickness of the pot.
6. A biscuit-fired bowl is used as the form, lined with an even sheet of
white clay, the same thickness as the rodi mark out the design guide line
with dividers.
7. The untidy edge around the top of the bowl is trimmed away with a sharp
craft knife.
8. the build-up of the design begins, starting from the centre and working
out wards.
9. the slices of the rod are laid in with slip, with little effort being
made to keep the inside surface clean.
10. Once the design has been completed, the inside surface is cleaned with a
metal kidney scraper. A protective mask should be worn.
11. the inside surface is given a final cleaning, first with coarse wire
wool and then with fine wire wool.
12. The pot is carefully removed from the form and the white liner coating
is outside surface scraped away with a razor blade. This is easier than a
knife, because it can be bent to follow the curves of the pot. The surface
is then cleared with coarse and fine wire wool.
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SATURDAY, NOVEMBER
25 2006