Newish conservatory wall - paint bubbling...what to do?

[Wizwoo]

Hello,
We bought our house about 18 months ago and the previous owners had recently added a conservatory. During last winter we noticed that the paint seemed to be bubbling and becoming flakey. I've now brushed some of it off in the hope to redecorate...but I'm not sure what to do.

I want to avoid it happening again but don't know what would have caused it. I've taken some photos and added them to flickr here:
http://www.flickr.com/photos/44911917@N08/4120999243/
http://www.flickr.com/photos/44911917@N08/4120998817/
http://www.flickr.com/photos/44911917@N08/4121769908/

The last one shows some white salt like residual that also appears.
Any ideas? Cheers.

 

[LJW61]

Its called efflorescence, the water in the plaster drew it out of the brickwork
you just need to brush it off & sponge out the 'salts' .. It may take some time to dry out completely

 

[Wizwoo]

OK - thanks for that LJW61. So if I rub down the whole wall what do I need to sponge it down with?
Plus should I go over it with anything in particular before painting with emulsion?

Cheers W

 

[LJW61]

Youll have to keep repeating the process until clear of salts (could take months) ..or... Just try seaing l with a couple of coats of oil-based undercoat before an emulsion top-coat

 

[Wizwoo]

OK...oil based undercoat. Any particular product you can suggest (not really sure what it is)

 

[LJW61]

Any white undercoat - Crown, Dulux, Leyland, Johnstones etc. , so long as it doesnt say 'Quick Drying' or 'Acrylic' (theyre water-based) on the tin it'll be oil-based , ie. needs white spirit to thin & clean (look on the back of the can ) ..