Our Victorian house was recently professionally painted - the job finished a few days ago. Last night it started raining, and this morning there are many places where the paint is now bubbling and blistering.

What could have caused this?

Note that:

  • Power washing did occur - but plenty of time went by (multiple days), in a warm and dry climate, for that to dry before painting started.
  • Some surfaces that are now bubbling were primed, others weren't.
  • There hasn't been rain in a long time, so the wood of the house was thoroughly dry.
  • The painters seemed to have been fairly careful about cleaning surfaces after preparing (scraping, filling, sanding) and before priming and painting.
  • Conditions were pretty ideal during painting - dry, mild temps (60s to 70s), little to no wind.

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  • 1
    Wow. There must be something going on that isn't in your description. Everything you mentioned sounds ideal. The fact that even primed areas blistered is a real head-scratcher. What type and brand of paint?
    – isherwood
    Nov 21, 2018 at 20:11
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    There's a fairly distinct line in the last photo where blistering ceases. Any idea what that's about?
    – isherwood
    Nov 21, 2018 at 20:13
  • 2
    It also appears to be all the colors of paint and different underlying materials are affected. How odd. I'm no expert in the mechanics of paint bubbles, but it appears as though the material is off-gassing, maybe? It almost looks like paint stripper was applied. Be sure to keep us updated as things progress. What does your painter say?
    – Tim Nevins
    Nov 21, 2018 at 20:50
  • 1
    Did they use a detergent with the pressure washer?
    – isherwood
    Nov 21, 2018 at 21:02
  • 1
    Thanks all! Some details you requested: Brand of paint is Benjamin Moore Regal Select exterior, freshly purchased from local dealer. As the rain has continued, blisters have spread - there is no indication they line up with brush marks or other boundaries (like underlying primed vs. non-primed areas) - plus some blistering areas were sprayed, some brushed, and some roller brushed. No paint stripper was used, no bleach or detergent was used in the power washing. The previous paint, which was applied at least 8 years ago, had minor hairline cracks in some areas, but no blisters.
    – Cooper
    Nov 23, 2018 at 17:41

1 Answer 1


I'm not an expert in the chemistry of paint so I did a little research and found this.

As the paint dries at different rates, it begins to pull and contract on one side, and stretch on the other, causing a bubble to form. The other way this can happen is if it rains on paint before it has dried completely.

Bubbles that occur on paint after it rains almost always happen very soon after the paint has been applied, and before it has had a chance to dry properly – often within the first 24 hours, although it could happen up to a week or more after the application.

Ref: https://www.homelogic.co.uk/exterior-paint-bubbling-after-rain-heres-what-to-do

Not sure if this helps but it seems to fit your description.


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