paint peeling/reacting on plaster coving

[stebed]

I am doing some work in a friends house. The coving was stripped right back to plaster as the old paint came off with the wallpaper stripper. I painted it with Dulux white emulsion and in a few places it cracked and peeled off. I have scrapped of the loose applied some Dulux plaster sealer (as they had a tin) and re-emulsioned and that has reacted also.

Any suggestions to what is best to seal the coving with as cleaning paint off it 3 times is no joke!

Thanks

 

[ellal]

you need an alkaline primer...

 

[stebed]

thank you