enter image description hereenter image description hereenter image description hereI have just rolled a second coat of emulsion (Farrow & Ball, brand new tin) onto a bedroom wall and an hour later noticed that a sweep of the wall (a few inches wide) has hairline cracks. I’ve not been aware of this ‘sweep’ before so am almost certain that it appeared today. The first coat was applied a week ago, so the surface was dry; and I’ve no reason to believe the wall was dirty when I painted.

Can anyone suggest what might be causing this and what I should do?

There was no wallpaper paste residue on the wall before I started this job, but before the paint went on last week I did have to fill some hairline cracks in this (and other) areas with Polyfilla. The odd thing is that I didn’t notice the cracked paint after the first coat was rolled on; it seems to have appeared only today (after the second coat was applied).

Following the suggestions given below, I sanded down the offending areas, cleaned the wall, cut out the top and sides, then next day rolled a fresh coat (carefully not using too much paint). While the original area looks somewhat better, the hairline cracking is now along the top of the wall and in other patches. I’ve not had this happen before. The only thing I can think of doing is to start again on this wall - this time using a primer first. Does anyone know what is going on to cause this?

  • 1
    Given you allowed for ample time between coats, it appears the paint was applied too thick to that particular spot.
    – Mikael
    Nov 18, 2019 at 16:23
  • Thes look like areas that were patched with spackle or sheetrock mud. It is necessary that patched areas be allowed to dry completely, be sanded and spot primed. After the prime is dry paint with top coat. Without priming the topcoats can interact undesirably with the compound used.
    – Kris
    Nov 20, 2019 at 15:58
  • After reading your edit and noticing the timeline between the original question and admits I think you may be rushing the process a bit.
    – Kris
    Nov 20, 2019 at 16:01
  • I haven’t put any spackle on myself (at the top, by the architrave). Would this paint effect still happen if spackle had been put on years ago and not applied properly as you suggest?
    – Winstonne
    Nov 20, 2019 at 16:10

1 Answer 1


That's exactly what happens when painting over remnant wallpaper paste. Or, if a white glue was used on a wall repair.

The only remedy is to scrape the offensive stuff off, wipe several times with a wet sponge...until no longer slippery and re-prime/paint.

A skin-thin application of Spackle/plasterboard compound can restore the scraped areas to paint elevation beautifully before re-priming/painting.


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