During the winter months, water vapor in the air comes into contact with windows in the house and condenses on them due to the cold outdoor temperature. This can result in unwanted ice buildup on the windows. And in the case of wooden window frames, this can result in rotting of the wood due to prolonged exposure to moisture.
Calcium Chloride can be used to reduce this problem. It has strong attraction for water so it acts as a dehumidifier.
Calcium Chloride is commonly sold in stores as deicer salt for melting snow and ice. It’s best to buy it in pure form, without other salts mixed in, as this can lower the effectiveness. There should be a label on the container telling you the content of the deicers. If you can’t find the name ‘Calcium Chloride’ look for the chemical symbol instead: CaCl2.
Put the Calcium Chloride inside reasonably large open containers and place them near the windows with the moisture problem. It will gradually absorb water vapor from the air and reduce the amount of water that comes into contact with the windows, leaving them dryer. See the figures below.
After a few days or so, and depending on how humid it is in that part of the house, the Calcium Chloride will become completely saturated with water. At this point you can replace it with new (dry) Calcium Chloride or dry it out using high heat. An outdoor barbecue will suffice. Once it’s completely dried out you can reuse it.
It can also be used in the warmer months to help dehumidify your house.