Bubbles in newly painted wall.

by **Andy Cross** » Thu Jun 03, 2010 9:50 pm

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?

by **stoneyboy** » Sat Jun 05, 2010 11:49 am

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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by **JRS** » Sat Jun 05, 2010 7:44 pm

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.

by **Andy Cross** » Sat Jun 05, 2010 8:15 pm

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

by **stoneyboy** » Sun Jun 06, 2010 8:10 pm

Andy Cross,
Something like 3or4:1 depending on the thickness of the emulsion - it needs to be really watery.
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by **JRS** » Wed Jun 09, 2010 12:46 pm

Andy Cross wrote: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.