"Lobster" wrote in message
...

I laid a bag only yesterday (Wickes). No mention of PVA anywhere - just
clean the surface and lightly dampen.

Well, I bought my bag today - also Wickes as it happens. I'll do no
more than reproduce the relevant text from the back of the bag below, as
obviously you missed the salient points when you read it:

"Dense Concrete:
Prime with Wickes Building Adhesive mixed with water in the ratio of
1:1. Allow to dry before laying levelling compound.

Porous Concrete:
Just before application of the levelling compound, lightly dampen the
concrete surface with clean water but avoid leaving pools of free water.

Very Porous Base Concret and Lightweight Screeds:
Prime the surface with Wickes Building Adhesive dliluted with 3 parts of
water to 1 part building adhesive and allow to dry."

Obviously they have changed the bag design or havc two suppliers or
something. Have just checked on the other two I have and there is no
mention of this.
What counts as "dense concrete" ? I still would have thought most
examples were in the second case and so no PVA is required.