On 26/04/2012 16:32, Rednadnerb wrote:

IMO thinning water based paint is never a good idea. It "breaks" the
emulsion so that some of the paint's properties are lost. Best to just
buy a paint that isn't as thick as custard to start with, which is often
the own label stuff in a tub.

Unless it is new plaster.

You need to consider what happens when you add water to paint. It
doesn't dilute the paint and the water tends to do its own thing once
it's on the wall. I know it's common practice but some very basic tests
would show that it isn't sound practice