This document discusses various ceramic firing techniques:
1. Salt firing involves introducing salt into the kiln to produce a hard glaze through chemical reactions between salt vapors and clay surfaces.
2. Raku firing removes pots from the kiln at maximum heat, using thermal shock to create fractured or "crazed" glazes that are then smoked.
3. Naked Raku results in unglazed clay surfaces.
4. Saggars contain materials like organic matter, metals or salts to produce colored patterns through chemical reactions during firing.
5. Horsehair Raku involves laying smoking strands of horsehair directly on hot pots removed from the kiln.
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3. “Salt firing is a vapor-glazing process where
salt (sodium chloride) is introduced into
kiln firebox at high temperature. The salt
vaporizes, and sodium vapor combines with
silica in clay surface, forming extremely hard
sodium-silicate glaze” [1].
4. “The process of Raku firing differs
from other firing methods because
the pots are removed from the kiln at
their maximum temperature.
Thermal shock of this rapid cooling
is stressful on the pottery. It is
achieved by using an open clay body.
The porosity of the clay body acts
like a shock absorber, preventing the
body from immediately fracturing
when the pot is removed from the
kiln. Raku glazes are often
fractured, which are referred to as
Crazing. These crackle glazes are
enhanced by the post firing smoking
of Raku pots that embeds carbon
into the crackles of the glaze” [2].
5. “Naked Raku is as the
name
suggests, naked, meani
ng that the end result
has no glaze on it, just
the bare clay surface.”
[3]
6. “A saggar is a container surrounding the
ceramic ware as it is being fired in the
kiln. The purpose of the saggar is to
provide an environment for fuming.
Various materials such as garbage,
seaweed, straw, sawdust, wood excelsior,
magazine pages, copper or brass wire,
salt, copper carbonate, iron oxide, cobalt
carbonate are placed in the saggar or tied
to the pieces. At the firing temperature,
these create a "fuming" atmosphere and
the chemicals are transferred to the
surface of the clay to form random and
serendipitous patterns and designs of
color. The color range is black, gray,
pink, maroon, orange, blue, green and
other colors depending on what
chemicals are used in the saggar” [4].
7. “Horsehair raku is another technique
that requires no glaze.The piece of
pottery, which has previously been
bisque fired, is loaded into the hot raku
kiln. At about 1400 °F it is removed from
the kiln with long tongs and set upon a
turntable.
Quickly, and carefully, strands of
horsehair are laid on the surface of the
pot.They immediately "frizzle" and
smoke. The burning hair leaves its mark
permanently on the face of the pot. The
smoke also leaves its mark giving the
piece a smoke "blush". Once the desired
pattern of burned hair is complete the
pot is allowed to cool naturally.
Afterward the ash residue is washed from
the pot and when it is thoroughly dry it is
waxed and buffed to a soft sheen “[5].
8. “Raku is a pottery technique that
has it's origins in 16th century
Japan. We are pretty sure that it
was developed by Korean potters
under Japanese rule but the exact
circumstances of it’s development
and in what context it was
discovered is a mystery. The raku
technique, like other pottery
techniques such as salt glazing
and pit firing, primarily revolves
around it's firing process
although involvement with raku
often goes much deeper into its
philosophy, roots, and cultural
significance. Traditional raku and
western version of raku are
similar in many ways though
there are some significant
differences” [6].