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Controlled Reduced Cooling 4 |
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Putting various
ex-anagama pots
through the gas refiring process we looked for perceived improvements
and were immediately encouraged by the fact that on this pot a heavy
deposit of glaze from Forest Red Gum, originally yellowish brown in the
image on the left, was transformed by the
refiring into black, as shown in the image on the right. Other changes
on the pot were less dramatic, but also to our liking.
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| As expected from
previous
refirings the reds associated with shino glazes were intensified by the
gas refiring process. This potentially red glaze, an iron red produced
by using an iron rich glaze in a shino recipe,
substantially off the pace as it came out of the anagama
(left)
was greatly improved to our eyes (right). The ash glaze on top of it
was presumably from Blackwood as this time it became yellowish in the
refiring, rather than black as in the image above. |
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One of the reasons
we chose to
use Blackwood as a fuel is that where the resulting ash glaze was thin it produced a red blush, and
as it thickened there was a gradation through the black edge effect to
the grey glaze and finally on to a thick green celedon. The red blush
and the black edge effect were enhanced by the gas refiring. In the
compound image at left all of the sections are examples of Blackwood ash glaze. None of the examples have been refired. The
slightly olive section at bottom right is the result of some oxidation
in the anagama firing. Neither of the two sections on the left changed
toward olive during gas refiring. The grey section at top right of
the image also was unaffected by gas refiring, and this was a major
concern. This color can be quite common in Blackwood firings, and it
turned out that the only thing we can think of to do is to
try to
avoid it. |
| To avoid widespread
occurence
of the grey Blackwood ash glaze we have concentrated on encouraging
situations where the Blackwood ash glaze rapidly changes from thick
celedon to red blush or bare clay. These stacks of narrowly separated
plates or bowls are useful, as is upside down packing, and
the use of shields. We do not usually refire
anagama pots
with gas, nor do we refire anagama pots in the anagama, as
our
main allies in controlling the thickness of the natural ash glaze are
the flame paths themselves, and we do not want to confuse the issue
with conflicting flame paths from consecutive firings.
Because of
the physical shape of seashells, and the presence of sodium ions in
their composition, they are very useful in guiding flame
paths
while at the same time encouraging red blushes as result of the sodium. |
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