Andy Hall wrote:
On 2007-01-03 14:40:50 +0000, Grunff said:

The Natural Philosopher wrote:
Grunff wrote:
PVA them first.


Don;t bother. Waster of time. Makes the adhesive take longer to set
as well.

Well, although I can't say I've tried with and without, my reason for
always PVAing is to provide a dust-free surface. Both ply and PB tend
to be quite dusty, especially if you've been plastering/filling in the
room. A coat of PVA provides a sound, dust-free surface to tile onto.

I was curious about this one, so I contacted the technical departments
of three leading adhesives companies - BAL, Dunlop and Ardex.

I can't believe you take any notice of what manufacturers say. It either
works or it doesn't and, in this case, you can tell when you slap the
first tile on. If it needs sealing, then seal it. I think perhaps you're
looking for certainties in situations where the conditions of use are
unknown.

One said yes and the second said no and the third said that it didn't
matter. I haven't got my notes with me and can't remember who said
which. Either way, I'm no further forward.

Then I discovered that they are all owned by the same company.