"Chris Holford" wrote in message
...
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?

That's exactly what happened to me. Had to take apart the plumbing and out
popper a solid, rock-hard cylinder of re-crystallised sodium hydroxide. I
presume that as it was put down the sink hot and left, it crystallised when
it cooled, completely blocking the sink.

I also tried hydrochloric acid and it didn't work for some reason. It
should!

You could try and siphon out any liquid and then pour boiling water down the
plughole. That may put the caustic soda back into solution.