In message , Derek Geldard
writes
On Fri, 05 Oct 2007 18:34:44 GMT, Lobster
wrote:

The compartment/cover is quite a complex bit of gubbins - would they
really have fitted it if it was totally superfluous?


It was invented in the days when dishwasher dertergents were powders
and if the powder was just put into to the wash compartment it would
have gone down the drain before the main wash started if the machine
did a pre-wash or rinse.

The first machine we had had a compartment for detergent for the main
wash, but the detergent for the pre-wash was just put in a pile on the
inside of the door near the bottom.

I believe today the tablets we have dissolve at a controlled rate so
they can do pre-wash, main wash, and rinse all in one tablet. Whilst
softening the water at the same time. :-)

That accords with my experience. I accidentally let the machine run a
Pre-Wash having put a tablet in. The tablet had been released and was
sitting on the bottom, minimally corroded.

--
Si