  The surface tension $\sigma$ of the confined-deconfined interface is
calculated in pure $SU(3)$ lattice gauge theory at finite temperatures
employing the operator and integral methods on a lattice of a size $8^2\times
N_z\times 2$ with $N_z=16$ and 40. Analyses of non-perturbative corrections in
asymmetry response functions strongly indicate that the use of one-loop values
for the response functions lead to an overestimate of $\sigma$ in the operator
method. The operator method also suffers more from finite-size effects due to a
finite thickness of the interface, leading us to conclude that the integral
method yields more reliable values for $\sigma$. Our result with the integral
method $\sigma/T_c^3=0.134(16)$ is consistent with earlier results and also
with that obtained with a transfer matrix method. Result is also reported on
$\sigma$ obtained on a lattice $18^2\times 48\times 4$ with the integral
method.
