On Wed, 21 Dec 2005 01:28:39 +0000, The Natural Philosopher
wrote:

I used to have a chart given out with one of the process plant magazines
each year which showed a selection/suitability chart for materials used with
various reagents. AFAICR it showed pvc pipe to be perfectly suitable for use
with 36% HCl and (not at the same time) 40Twaddle Caustic soda so your
dangerous to plastic comment seems a long way from the mark

Well, I had a plastic sink, and it used to pickup up a LOT of tea stains,
and I used caustic to remove em.

After a few years it was brittle and flaky on the surface. Like non U PVC
gets in sunlight.

It may not have been PVC, but it definitely degraded.

Hi,

Probably depends on the plastic, I've found liquid dishwasher
detergent can etch microscopic lines in clear hard plastics, which
catch the light and are quite noticable.

It is sodium silicate and not hydroxide, but comes in an HDPE bottle.
Ideal for softening baked on crud, but makes the pump squeak which is
a bit worrying. Might be good for unblocking drains though

Anyway, I wonder if the OP has unblocked their sink yet...

cheers,
Pete.