  We report on the observation of freely decaying capillary wave turbulence on
the surface of a fluid. The capillary wave turbulence spectrum decay is found
to be self-similar in time with the same power law exponent than the one found
in the stationary regime, in agreement with weak turbulence predictions. The
amplitude of all Fourier modes are found to decrease exponentially with time at
the same damping rate. The longest wavelengths involved in the system are shown
to be damped by viscous surface boundary layer. These long waves play the role
of an energy source during the decay that sustains nonlinear interactions to
keep capillary waves in a wave turbulent state.
