Mist coat failing

[wolfgang]

What's my best strategy for going forward? Newly plastered walls, left 4 weeks to dry. Applied a mist cost, but probably far too thick, around 25% water dilution of a white emulsion.
I was trying to tape the top of the walls on my second coat for a sharp border where the picture rail would be, but the making tape ripped entire sections of cost +mist clean off the plaster.
If I rub the edges with my fingers, the paint just rolls up and keeps coming off.
Where do I go from here? How do I fix this?
Sanding, new mist coat and bending it in, hoping the paint in the rest of the room has enough adhesion not to come off on its own?

 

[johnny2007]

Did you sand the plaster before painting?
I wrote a thread a few years ago with different tests done on new plaster.
The best results were obtained by rubbing plaster with sanding pad (medium grit, grey if i'm not mistaken) and mist coat with dulux diluted at manufacturer recommendation (i think 25%)

 

[freddiemercurystwin]

@opps

 

[wolfgang]

No, I didn't. The plasterer just said to treat with a mist coat.
I'm thinking to sand down and feather/blend it in. I won't be able to use take to create top white band above the main wall colour, but that's a problem for another day.
Would that work? What grits would you recommend? Sand by hand with a foam pad or every so lightly with my Mirca RO?

 

[johnny2007]

New shiny plaster: to sand or not to sand before painting?

This became a very heated argument yesterday between decorators working at my former customer new built. Plaster is dried for 4 weeks and it's very smooth and shiny. Some decorators want to give it a quick sanding before mist coat, others say it will ruin the perfect finish. Got to say, I've...

www.diynot.com

Here it is.
Dilution was 25% not 10%