tester wrote:
Hi,

What's the best place to get rid of plaster cleaned from the mixing
bowl, trowel and other items - paper then in the bin or is there a
better way?

You can leave to dry in a newspaper or any kind of bag, then bin it - it's
less messy than when it's wet

One thing I do not want to do is pour it down and drain / loo - that
would block them would'nt it?

Yes, skimming sets even under water.

Slop buckets and trowelling up water can be poured onto the soil - it's
mostly gypsum and is harmless....school chalk is made out of the same stuff.