The present study was conducted to explore the colouring potential of red calico {Alternanthera bittzickiana
(Regel) G. Nicholson} leaves and to improve colour strength of dye using gamma radiations
followed by mordanting process. The results showed that red calico plant leaves could be an excellent
source of natural dyes for textile sector. Copper sulphate (1%) and tannic acid (1%) were the best pre- and
post-mordants, respectively to improve the colour strength and colourfastness properties. The results
from dyeing indicated that gamma ray treatment of 15 kGy was the effective absorbed dose for extraction
of dye and surface modification of cotton fabric. Dyeing of cotton fabric with red calico leaf extract at
60 C for 50 min using dye bath of pH 7.0 and salt concentration of 6 g/L produced good colour strength.
Gamma ray treatment of cotton reduced the amount of mordants and improved the colourfastness
properties