Paint blisters (emulsion)

[Stephen]

Hello,

As you may have read in my other post, I have been rollering a ceiling. The ceiling was plastered and allowed to dry and then I painted it with Blue Hawk plaster sealer from B&Q and allowed that to dry. When I rollered the ceiling 99% went on fine but in one or two patches I got some tiny blisters.

I made the mistake of scraping the blisters but this made them worse because they kept blistering at the edges so I scarped back more and got bigger and bigger bald patches!

I left some blisters alone and to my surprise, when the paint dried, they disappeared completely.

What caused the blisters and how can I avoid them in the future? Was the plaster not sealed adequately; I've never seen them on any other ceiling I have painted.

I have over painted the craters that I scraped out and they are staring to look more hidden but they can still be seen when the light hits them from a certain direction. What's the best way to remove these: some filler?

Thanks.

[Stuart Noble]

I've had this problem with gel type emulsions. Some are thick enough to stand your brush in. I think a fine surface filler applied with a plasterers trowel is probably your best bet, trying not to leave any excess that would need sanding.

[sm_jamieson]

This can occur if the plaster is dusty in places, and the emulsion does not "stick". But you say you sealed it ? Did you miss a few bits ? You can check with a light at a low angle where the sheen of the plaster sealer can be seen. Also, the thick emulsions can be worse for this. Simon.