Tom wrote:
Hi All,

Just wondered if anything has changed over the years - I always
understood that new plaster needs to be sized with PVA or equivalent
before painting etc., failure to do leads to peeling later on. Uneven
peeling at that, I've seen this so many times its unbelievable, there
must have been loads of inexperienced painters/builders/finishers in
the past. Trouble is the problems won't show up for years, by which
time they will have legged it.

But the current builders I'm using deny sizing is needed. Why? What
has changed? Have newer emulsions made this unnecessary?

Rgds., Tom

Bare plaster needs to be sized, although your reasons for doing so seem to
differ from the actual reason.
paper shouldn't peel regardless of whether the wall was sized or not -
sizing simply kills the suction of new plaster, making it easier to 'slide'
the pasted paper into position without the wall drying it out too much
during hanging.
Painted walls don't generally need sizing because they are effectively
already sealed.

If your new plaster is being left raw, you need to size it, you can use
normal paste diluted down from the usual consistency, and allow to dry
before paperhanging

--
Phil L
RSRL Tipster Of The Year 2008