pva timing

[marsaday]

I need to fill in a channel with bonding on my wall. Then i will pva and skim.

How long do i wait to apply the pva to the rest of the wall while i let the bonding go off a bit ?

Say apply bonding then wait 20 mins and pva wall. wait 30 mins and skim

 

[Richard C]

Are you re-skimming the entire wall or just the filling out & blending in the chanell?

 

[marsaday]

whole wall

 

[Richard C]

Fill out to the surrounding wall with Bonding, when set, tape the join well apply two coats of PVA thinned around 4:1, plaster while second coat is still tacky but not wet; never plaster over dry PVA.

Forgot to ask, what type of finish on the existing wall? If paint what type, matt, acrylic, gloss? You may need additional preparation.

 

[paul78]

yep agree with rich, i work with a spread who insists on his pva bone dry before he skims

dont quite get in myself but each to their own and im sure hes the minority who does that.

even showed him the back of a tub of pva where it explains to "skim while tacky" ....... but what do i know

 

[roughcaster]

i work with a spread who insists on his pva bone dry before he skims

I wouldn't call him a spread.

 

[stevethespreader]

you will be better off time wise to give the wall its first coat of pva before you use the bonding, as you are waiting for the bonding to dry the first coat of pva will be drying out at the same time, rather than wait till the bonding to set before giving it its first coat

 

[marsaday]

The finish will be emulsion.

I have pva'ed the wall today. So it is now all sealed up.

So i will apply the pva to the wall before the bonding and then the bonding. Wait for both to go off a bit and then skim. Plus i also need to apply skrim around the edges.

cheers

 

[stevethespreader]

The finish will be emulsion.

rich was asking what type of finish is on the wall already, is it painted and if so what is it? it may need more prep than just pva it may need a bonding agent if its glossy or shiny paint

 

[Richard C]

The finish will be emulsion.

rich was asking what type of finish is on the wall already is it painted and if so what is it? it may need more prep than just pva it may need a bonding agent if its glossy or shiny paint

 

[marsaday]

Right. The wall is old plaster and has emulsion on it.

I have scored the wall as well prior to pva'ing today

 

[Richard C]

Matt emulsion should not present too many if any problems but vinyl, acrylic or gloss can be a different story because it will affect adhesion. It's important to know what type of emulsion you have & how well it’s stuck on there cos that’s what’s going to be holding your skim coat. It’s worth doing a paint adhesion teast; stick a 400mm strip of 50mm wide masking tape over the paint, moderately rub your finger along it & then pull it off at a slow but constant pace; if the paint comes off your in trouble with adhesion for your new skim & you need to do extra prep.

I use an old trowel to seriously criss-cross score back to plaster any paint base I’m not entirely sure of & then use a very (very) stiff wire brush over the rest.

 

[marsaday]

ok, i will try the masking tape tomorrow.

If it does come off will a rub down with a wire brush be enough ?

Any more prep ?