On Sunday, 1 April 2012 09:34:05 UTC+1, Chris Holford wrote:
I thought it would be a good idea to put a little caustic soda down the
plugholes in the shower try. Unfortunately I was over generous and the
caustic soda granules seem to have congealed in the trap and blocked it.
Would be a big job to get to the trap. I've tried a plunger, and tried
neutralising with spirits of salts (NaOH + HCl H2O + NaCL, ie salt
and water). -still no joy. The drain hole has a white disk a little
below the opening which prevents direct poking.
Any ideas?
--
Chris Holford

Have you tried lifting up the centre of the grille. As showers often block with hair, a lot of them have a disc suspended below the drain grille to catch the hair. The drain grille just lifts out together with the disc so that the hair can be removed. If it is covered with NaOH I would be more than a bit careful.

John