High suction background

[Ste8090]

Hello
I'm planning to dot and dab a window reveal but I'm not sure about the underside of the lintel I tried to damp it down before putting the board up but it just keeps drying out I've used a whole spray bottle even brushing on water but it just keeps evaporating within seconds it is about 30mm what seems to be maybe sand and cement a lot harder than backing plaster so just wandering what sort of preparation is required if any thanks

 

[roughcaster]

Same as before Ste8090. Give it a damp down, then brush on some PVA right away whilst it's still damp. After that, let it DRY, an hour or so. After it has dried out, mix up some dot and dab adhesive ready for using, then PVA the lintel, leave it to go tacky, ( a minute or so), then dab the plasterboard onto the lintel RIGHT AWAY.
The pva you applied earlier will kill any suction, but be sure to dab the piece of plasterboard onto the second coat of pva while the pva is still wet/tacky. I've said that twice because it's important.

 

[Ste8090]

Thanks

 

[Ste8090]

Same as before Ste8090. Give it a damp down, then brush on some PVA right away whilst it's still damp. After that, let it DRY, an hour or so. After it has dried out, mix up some dot and dab adhesive ready for using, then PVA the lintel, leave it to go tacky, ( a minute or so), then dab the plasterboard onto the lintel RIGHT AWAY.
The pva you applied earlier will kill any suction, but be sure to dab the piece of plasterboard onto the second coat of pva while the pva is still wet/tacky. I've said that twice because it's important.

Thanks for the reply what ratio of pva/water for 1st and 2nd coat of pva will be needed?

Read more: https://www.diynot.com/diy/threads/high-suction-background.494465/#ixzz51YPJNCGr

 

[roughcaster]

I normally use 1 part water to 1 part pva, and quite often, neat pva. The more water you use, the "weaker" the pva.