New paint over plaster repair on bathroom ceiling has peeled the sealant layer off!

[miljee]

A new plaster strip was left to dry for a week; I then sealed it with dilute cheap emulsion, 2 layers with time between, then left that to dry for several days, then today went to roller on white B & Q Good Home bathroom ceiling paint. Within moments, it lifted off, taking the underlying sealant layer with this! The dark brown is unsealed plaster. We also had the entire kitchen and utility ceilings skimmed and I gave them the same treatment, and they've come up looking perfect, though I used Dulux Light + Space on them.

The other image is the other bathroom with the unpainted sealant on it awaiting painting which obviously I don't want to touch til I know what went wrong in the first bathroom!

Any ideas of what I did wrong? We're letting this dry, then I'll scrape it off, sand the edges, but do I repeat the process with dilute emulsion?

 

[opps]

I suspect that you over thinned the sealing coats.

The tin would have told you how much water to add, unfortunately, there is a lot of really bad advice on the web, with people recommend adding stupidly large amounts of water.

I have no idea what ratios of water you used, it may however be prudent to read the instructions on the back of the tin and follow those before applying any further paint. If you no longer have the original base coat paint, just dilute a small amount of the new paint- again, as per the instructions on the tin.