Bubbles in newly painted wall. General decorating topics, questions and answers. find help, tips and advice on completing your decorating projects

[Andy Cross]

I have just repaired a crack in a wall by filling and then sanding flat. I had to sand down to the plaster to remove the step then put a layer of white emulsion on before the end colour. While the paint was drying I noticed several bubbles appeared around the area of the crack. Anyone have any ideas why this happens?

[stoneyboy]

Andy Cross,
Did you thin down the first coat of emulsion? If not this is the most likely cause of bubbling.
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[JRS]

Never heard of thin emulsion blistering. What filler did you use. Was it over wallpaper, lining paper. Filler must be completely dry before sanding and painting and dust free.

[Andy Cross]

No I didn't thin the first coat I didn't know I had to. How thin would you make it?

[stoneyboy]

Andy Cross,
Something like 3or4:1 depending on the thickness of the emulsion - it needs to be really watery.
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[JRS]

No I didn't thin the first coat I didn't know I had to. How thin would you make it?

This may be why it blistered. 70% water or just get bnq stuff 5r for 5l and its more or less water. Thick/full emulsion will just sit on the surface of new plaster.