After allowing our new plaster to dry out thoroughly we have mist coated using watered down trade emulsion. One coat watered down to 50/50 then a second coat watered down to 70/30.

 

Mostly fine but...

 

As the photos show we have some areas where very little paint seems to have taken - notably in corners where the roller wouldn't reach and a brush had to be used. I noticed myself when trying to paint these corner areas with a brush (spouse did most of it) that the paint didn't seem to want to stay on the wall, almost as though it was being repelled, trying to brush more on only seemed to brush out remove paint already applied.

 

We also have some areas where there are visible splash marks showing - something maybe splashed on the wall when the ceiling was plastered ? PVA ?

 

What should we do ? Do we need to sand these areas and re-mist ?

Others will be along soon . But I’ve experienced exactly this and I did indeed sand back and repaint .

I usually use the same plasterer , stuff like this minimal . But when he’s unavailable used a different plasterer where this becomes more pronounced . I always assumed it was down to a ‘messy’ poor quality plasterer  

Edited August 7, 20251 yr by Pocster

With a mist coat you need to work out your finished paint system and work backwards. 
it is a big problem in the painting industry at the moment of using 50 year old technology of a watered down contract emulsion then going over the top with one of the new technology scrubbable matts. 
 

the two types of paint don’t work and the hard wearing scrubbable version will pull the mist coat off the plaster. 
 

look at your top coat and follow the instructions on surface preparation. 

Attach some more photos - seem to have over compressed the earlier ones.

 

I note on the external corner one side is fine, the other side if affected (see photo). Suggestion is that external corners are affected by which way the plasterboard is running/whether there is a cut end ?

 

Spoke briefly to plasterer. He said yes he had had this happen before and said it would need to be sanded down gently and re-misted. It was because he sometimes used a bit of PVA in corners and drip marks also likely PVA from doing the ceiling second rather than first.

1 hour ago, Russell griffiths said:

the two types of paint don’t work and the hard wearing scrubbable version will pull the mist coat off the plaster. 
 

look at your top coat and follow the instructions on surface preparation. 

Oh yes, bring me more problems to worry about. Why is this building malarkey such a PITA.

We haven't even chosen top coat paint yet - far too many other issues to resolve.

 

https://youtu.be/VoP1E9J4jpg?feature=shared

I had that here and there too. Light sand to flatten it and another coat. I should add that I used paint suitable for mist coating without watering down. No issues with the hard wearing top coat pulling the mist coat off. I did have that problem on the bottom of one wall but the prep was exactly the same as everywhere else. 

Edited August 7, 20251 yr by Kelvin