Skimming over sand & cement

[jimmbo]

Hi guys,

I’m after bit of advice, please.

I blocked up the opening between our living room and dining room with aerated blocks and then rendered with 4-1-1 mix to bring level with the existing wall. I scratched the render to leave a key for plastering.

I was going to use thistle multifinish to level off n blend into the existing skimmed/painted wall.

What do I need to prime it before plastering? I’m assuming I need to coat the render with something to stop it sucking all the water out of the plaster and a bonding agent over the existing painted parts?

Many thanks

 

[roy c]

Did you put a "scratch coat" on then a float coat?

 

[jimmbo]

Yes

 

[jimmbo]

I mixed up some PVA 1:5 n painted all over the render n about 6-8” overlapping original painted wall. Left to dry overnight n gave it another coat of thicker PVA (2:1). I left it to go off, till it was still a little tacky not completely dry.

I then mixed up some multifinish which I had left over from skimming some boards up last year. Big mistake, I guess?! It seemed ok until I started putting it on. But it just all went off within a couple of minutes!

Obviously wasted most of the mix, which is ok, but I’m unsure now what to do about the stuff I did manage to get on the wall?

It does seem ok at moment (19hrs later). But is it likely to crack and make doing the rest of it impossible to get right? Should I re-PVA the whole area - going over the fresh plaster? Or do I need to remove the new plaster before retrying?

Many thanks