How to rescue a painted plaster wall? I have a short time ago found out that I should have...

I have a short time ago found out that I should have hermetic the plaster walls I have a moment ago painted before putting the paint on. It be water base paint, and I just discovered that mask tape take the paint off!

Apparently I can use watered down paint to prime the walls first, but can this be done after drawing, or do i need to sand adjectives this paint off and consequently do the watered down paint?

Any suggestions welcome!
I wanna re do my room over.?
Seal it with a coat of Unibond

Room colors?
I think you requirement to let it dry for a couple of weeks and see if it adhere to the plaster. The first coat is usually a primer, or sealer coat and you are right its watered down finish paint. The reason its watered down is to hold it soak into the plaster and hold on to it. Then when you put the finish coat on it adheres to the trademark coat
You kinda did it backwards.
Good luck, and when all else fail read the directions
Creative bedroom decorate tips?
Answers:    If you use a environment grain sandpaper and do the adjectives wall you can get it looking fine again..Once you enjoy sanded dilute your paint by in the order of 15% then do the undamaged wall so it is all evenly applied.Then recoat it adjectives again once the first coat has dried, typically about 5 hours within optimum drying conditions...
For future quotation use should use a low tack masking video available at most DIY stores....