In message , Marland
writes

Ive used a similar mixture but using granulated sugar instead of the sand,
Has the advantage that it washes away cleanly down the plug hole and
dissolves in hot water.

'Back in the day' we used to use a mixture of washing up liquid and
whatever washing powder was in the cupboard. Tide, OMO etc. Good for
cleaning, but probably not terribly good for the skin.
--
Graeme