PVA and it's use

[markyyyyyy]

Just a general question. Sometimes a 5:1, 3:1 or even neat PVA is advised before skimming.

Is neat PVA used on a high suction background to provide more or a seal so it doesn't suck the moisture out of the new skin?

But when is a 5:1 waterVA mix used and when is a neat PVA applied before skimming?

 

[dontbelieveawordofit]

I often use neat pva , sometimes with a handful of sand in before skimming to provide suction control and adhesion.
I never use watered down pva for skimming.

 

[Wayners]

I never use neat pva. I just follow the advice on pva and they can be different from brand to brand. Not all pva is the same. I normally water down and coat and let that dry (day before) then 3-1 and if that hangs wet for 10 mins skim away.
For really porous surfaces beeline sealer (Pva emulsion as kills suction dead) then plastering pva 3-1 over and when sticky skim.
So many ways to do it and it's whatever works for you I guess. Some use to blue grit. Sbr is another popular one.

 

[dontbelieveawordofit]

i never use sbr for skimming , it’s a myth. similarly if you apply wet plaster to wet pva , expect it to slide down the wall and tear when your closing in.
Blue grit and similar products are almost always the way to go.
we’re all different

 

[lostinthelight]

If I get a variable surface wall I SBR ,leave 24 hours then bluegrit and in another 24 skim. Not practical for tradesman I guess but has always worked at my pace.

 

[dontbelieveawordofit]

your’e wasting good money on sbr . blue grit is more than good enough.
we’re all different.