The reduction cycle is
responsible for a wonderful and unique pallet of colors which occurs when
oxygen deprived molecules seeks the chemically bound oxygen from minerals that
are in clay and glazes.
classic example of a reduction glaze is "Chun Red" also known
"Copper Red", that dates back to the Sung dynasty in China.
Copper produces a green color when fired in a atmosphere rich in oxygen.
However in reduction conditions the glaze containing copper
can produces reds ranging in color from peach blossom to apple red.