On 01/04/2012 09:34, 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?

Whether you've ended up with a plug of salt or soda, it dissolves
eventually. This can happen even in a bucket if you don't add the
crystals gradually.