painted fascia has chalky fog-like marks that come and go

bug

Hi, I searched your forum all afternoon and can't find an answer.
My husband painted the fascia dark brown like the rest of the house last summer (during the day, dry, not humid weather.) This past spring we noticed white mold or fog like lines that show up a few days and then other days it dissapears!!

What happened and what can be done?

tia

Nestor_Kelebay

Tia:

I think the problem may be something called "Frosting" since this is a dark paint you used. It's caused by the calcium carbonate extender pigments dissolving in any rain that falls on the paint, and then drying on the painted surface to form a salt that's white and powdery, very much like chaulking.

The recommended solution is to remove the calcium carbonate by sanding it off, painting over the affected area with an oil based primer (that will prevent the moisture from penetrating into the paint) and repainting.

Go to:
http://www.paintquality.com
Click on the grey "Solve your paint problems" link
Click on the peach "Exterior" link on the right side
Look at all the different paint problems, especially chaulking and frosting.

Does either one look like what you're experiencing?

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Tom Struble

fortunately or unfortunately the answer to most paint problem is sand off and repaint

bug

Thanks, I was afraid of that.