The Chinese gallnuts were weighed, washed, crushed to the
average particle diameter of 1.5 mm and soaked in distilled water
using different liquor ratios of 1:20, 1:30 and 1:40 for 12 h at room
temperature. The extraction was then performed in a 2000 mL
cylindrical stainless steel container equipped with a mechanical
stirrer and condenser by use of distilled water for 30, 60 or 90 min
at 70,90 or 100 C. The agitation speed of 80r/min was kept
constant during the extraction process. After extraction the liquor
was cooled to 20 C, filtered to remove any insoluble residues and
the extracted liquor from successive cycles was mixed and
concentrated by boiling to yield a 10% dye solution based on the
initial weight of Chinese gall