In article ,
The Natural Philosopher writes:
wrote:
leave 1/4 - 1/2" gaps, the plaster squishes thru and bonds them
together. Otherwise the joints jhust crack.

Or use the sticky open weave (glass?) tape to tape the joints, which is
equally as good.

.... a.k.a. scrim tape.

The gap allows the boards to be bonded.
The scrim tape stops the plaster falling away if there is
any movement -- you just get a hairline crack which will
be easily filled with paint. It won't bond the boards
together by itself though -- you still have to do that.

--
Andrew Gabriel