In article ,
Janet Tweedy wrote:

In article , tina
writes

I'm also going to buy a couple of 8ft by 4ft plaster boards & chuck
those in as well in the hope that the gypsum in the boards may help to
break the solid clay up a bit.


Buy? Use new plasterboard? If gypsum is a good idea, I'd have
thought finding it in skips where people are doing building work
would make more sense. Alternatively, to save you handling and
breaking up large cumbersome boards, why not buy the plaster
unused in powder form?