What ratio does the PVA mix need to be? I am skimming over old (flat) patched plaster, some parts are hard wall, some are multifinish and others are something unknown... Also, do you have any opinion on budget non-brand PVA vs brand stuff?
Answer A milky consistency generally works well. On surfaces such as you describe - two thin coats of PVA work better than 1 thick coat. If the PVA is too thick it lays on the surface and is not absorbed into the wall leaving it at risk of peeling off. When it is thinner the PVA can run into the pores of the old surface and gain a good bond. However even though this will achieve a good bond it may not adequately control the suction so further coats may be needed to ensure the new plaster does not dry too quickly on the wall.
All brands of PVA should do exactly the same job - I am not aware of any practical differences other than economy. I suspect some brands of PVA to be thicker than cheaper varieties and therefore go further, but I have no idea which prove to be the best value for money - I tend to just buy the cheapest.
Paul
Oct 18, 2015
plastering by: Anonymous
builders need to move with the times, P.v.a. is ok in certain situations, S.B.R. is the better product prior to re-plastering. Also Unibond is just a brand name & is NO better than any other P.V.A.bond out there unless its the contractors grade.