sealing/covering(what with?)emulsion to stop blistering-HELP

[jamiller]

I am still having problems with bubbling up (2-5mm dia) of matt emulsion on one wall. If i apply another coat , the blistering re-appears (Probably due to contamination a couple of layers down!) Some of the bubbles disappear when dried, but some are still visible. I will have to sand down but would like to know if I can apply something to stop bubbling when I reapply colour. I am thinking diluted PVA? in the hope that the fresh emulsion will sit on top rather than bleed through to contaminated layer. Unless diluted PVA will in itself cause bubbles! Any suggestions much appreciated!!

 

[harrowbuilder]

This is a really tough one. Id be tempted to use exterior diluted PVA but be prepared for some filling/sanding when the bubbles come up again. Once you've sanded and filled, apply another pva to the areas you sanded. Then you should have a great finish when you apply final emulsion

 

[PartPapproved]

This is a typical problem that was caused by 2 things (a) lime in previous coatings eating away at the old paints thus making them loose (b) the more common reason is because after the walls were plastered they were not stabilized properly, pva is ok however there are specific stabilizers on the market which do the job much better and seel the plaster work, the reason for the bubbles is there is no adherement to the plaster behind , I have come across this many times and the only really effective way is to razor scrape all the loose paint off, normally back to the bare plaster then start all over again, trying to pva over the top of the old walling covering will not sort the prob for you. i know its a crappy job but trust me once you have done it you will see the benefits!

 

[Zampa]

I wouldnt use PVA its waterbased the same as the emulsion and when you apply the emulsion over it it may lift..plus you may find you get a crazed effect as the PVA is more flexible than the emulsion and as it dries it could cause the emul to craze.

Id scrape it right back as far as you can go and give it a coat of alkali resisting primer sealer....which is oil based., then make good and repaint

 

[jamiller]

is lining (then painting)the one wall an option, or would the bubbles activate and show through the paper. Thanks for all previous helpful comments.

 

[Zampa]

You can never tell or predict what will happen...you may get away with it...you may not, unfortunatly the only way to find out is to paper it....it could be a hard and expensive lesson.