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« on: 23 February 2014, 12:22:30 »
Maybe I should have known this. Noticed in my parents old house that brown drops of liquid were dripping down bathroom cupboard at high level. The house is not used much and there is no extractor fan. Went onto a painters forum and hey presto....
"Let's look at the bigger picture ....
Others have correctly addressed the ventilation issue. There will never be a solution if the ventilation isn't fixed.
The simple fact is that the cheapest bath fans move enough air ONLY if there's a very short, straight exhaust duct made of rigid metal. Any other duct run requires a bigger fan.
Just as important is the fact that no fan can take air out, unless there is also a way for air to get in. If there isn't a vent in the door, the door ought to stop an inch or two above the floor.
Painters face a special problem in painting bathrooms: leaching. Moisture that sits atop paint will leach pigments out of the paint, then deposit those pigments when they dry. Since iron is one of the pigments, we end up with 'rust spots' on the ceiling.
With all the technology we have, it's still pretty hard to beat good, old fashioned shellac for moisture resistance. Perhaps we might want to make it 'standard' to apply a coat of shellac in bathrooms- especially the ceilings."
