Eggshell type coating on victorian coving

[pls1]

Spent a few days trying to renovate some old Victorian coving which is badly flaking in quite a few places. The flaking surface of the coving seems to be very thick paint almost like an eggshell in thickness. I'm flaking it off with a palette knife that reveals the soft plaster of the coving underneath (& chips very easily )
The problem is it doesn't all come off very easily leaving the surface very rough and obvious that some of the 'coating' has flaked away.
What is the best way to renovate this before painting?

 

[curlyzoo2002]

hi im a qualified decorator

you need to scrape back all lose stuff to a solid edge. then fill the edges with polly filler or if you have a lot to fill get a bag of easy fill, its a big bag from B and Q for £10 once its filled and set( set means hard but not dry, Dry - White) fill it again then rub it down once its dry with 80 to 120 grade sanding paper.

 

[kbdiy]

Being of that age, it could be that the previous coatings were distemper - I found out the hard way many years ago. Test this by trying to wash it - if it dissolves into a chalky solution then almost certainly distemper and will all need to be washed off. If you try to emulsion over it will just soften again and will not stick.