On Mar 3, 11:05*am, 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


If emulsion is put onto new plaster, the plaster sucks the liquid out
of it, and the liquid contains the pva glue that sticks the paint
pigment on. So you get a weaker bond of paint to plaster.

There are 2 ways to address this.
1. Paint first with paint diluted 50/50
2. Paint first with just water, and after 5 minutes apply full
strength emulsion.

Both work fine, I find the latter much quicker.


nt