Paint adhesion and cracking

[AdamNichol]

Hello all,
Have something of a house of horrors with regard to painting . Have two problems, though they may be connected.

The first problem is with paint adhesion. In the hallway, living room, bedroom and ensuite I have encountered a situation whereby the application of a coat of paint to the walls causes a 'bubbling' behind the existing coat, which then lifts from the plaster and peels off the wall like a sheet of thin rubber . The hallway and bedrrom both had wall paper stripped before painting, the ensuite had painted walls. In each case, the walls were sanded and sugar soaped. When the original paintwork was completely stripped back to the plasterwork, the palster was sealed with plaster sealer before reapplication of paint. Any ideas about what is causing this as prepratory work does not seem to prevent it ?

Secondly, the paint to these walls has a tendency to split. Sometimes there is only a small area which looks like a series of hairline cracks stemming from a central point. However, the ensuite has a large section next to the window which looks like an aerial shot of very hard baked mud - lots of fracture lines, no particular point of origin. Previously, treating the cracked areas with plaster sealer before repainting cured this problem, but it has reoccured in the ensuite. I'm using reasonable quality B&Q paint for all these jobs. Anyone know what I'm doing wrong?

Thanks,
Adam

 

[confidentincompetent]

has a large section next to the window which looks like an aerial shot of very hard baked mud - lots of fracture lines, no particular point of origin.

This sounds a classic case of not removing all traces of old paste, The emulsion is livening up the old paste. The old paste should be wetted with sugar soap (not just sponged over ) then after a minute or so you'll see the paste 'gell up', get a large scraper/ spatula and carefully scrape off the goo. I usually strip a couple of drops and use the old paper to regularly wipe scraper clean, then finish off with clear water.. This is if the walls are to be painted and not paper'ed

The bubbling of old paint... probably someone previously has used a plaster sealer/pva did you try letting it all dry out before messing with bubbles? sometimes they simply go back when emulsion dries.
I dont use any plaster sealers for emulsion. Unless the surface is dodgy , then I might use a primer sealer, like zinnsser 123. Generally though for bare plaster! Use a thinned coat of emulsion 30/40% for first coat, 20% for next 1 or two coats = you wont ever have probs like your gettin now
Good luck

 

[AdamNichol]

Thanks for the reply.
You are probably right about the old paste. For unknown reasons the previous wallpaper peeled off with absolute ease . It was that spongy double ply type of wall paper and only left a few traces of the backing section - removed with a wet cloth and scraper .

As for the ensuite (paint onto old paint) going to give it a go over with dilute PVA and leave to dry overnight before repainting. Following advice elsewhere on the forum I have bought specific bathroom paint, but wondered whether its PVA/emulsion base would be an issue?

Thanks,
Adam