Learn about the impact humidity levels can have on items in your home.
Wood absorbs and desorbs water as relative humidity rises and falls, and in doing so it swells and shrinks. Low humidity often results in joints becoming loose, open or sometimes pull apart. As with all wood, it is important to maintain a consistent relative humidity, which depending on home location means providing humidity with a humidifier in colder, drier winter months.
Natural wood is the preferred material used to craft musical instruments because of its tonal qualities, but wood expands and contracts with changes in relative humidity. Low relative humidity causes damage to instruments when internal stresses created by wood contraction causes glue joints to fail or the wood to crack.
Books are affected by low humidity; over time the pages become more brittle and fragile. As paper absorbs and desorbs water, the dimensions of the paper changes, which accelerates deterioration and can lead to visible damage as wrinkling of the paper, flaking ink, or warped covers on books.
Low humidity can result in cracking and separating of wood. Mitered corners can separate. In pre-finished or engineered wood floors, floors can “cup” where the floor does not remain flat. “Cupping” happens when the top of the board is drier than the bottom of the board due to low humidity in the living space.
Cork is a natural product and will dry out even when wine bottles are placed on their sides. The top of the cork is exposed to the air around it. If the air is too dry, the top of the cork will dry out, shrink, crack and allow more air to come into contact with the wine. If wine bottles with natural corks are too dry, the cork will crack and air will leak into the bottle ruining the wine. For wine to age properly, temperature and humidity levels should be consistently maintained.
Art, especially, oil paintings on canvas can be impacted by low relative humidity. While, low moisture levels tends to minimize chemical change, they also tend to make the paint brittle and prone to cracking.
Maintaining stable relative humidity will reduce the effects of repeated absorption and desorption or water, which ruins stamps by making them brittle or discoloured.
As with other paper materials, low humidity leads to photographs becoming brittle and curling of the photographs. Low humidity can also result in the photo emulsion flaking off damaging the photograph.
Low humidity can result in cracking and separating of drywall seams. Wallpaper and the glue used to adhere wallpaper can dry out and become brittle and separate from wall, reducing the longevity of the paper.
Low moisture content in air with low relative humidity can result in releases of static electricity. While only mildly annoying to people, static electricity can damage internal components of computers, televisions, and other electronics.
References
*Studies have shown that keeping indoor air at an RH level of 40-60% reduces survival of flu viruses on surfaces and in the air compared to lower RH levels.
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American Institute for Conservation of Historic & Artistic Works (AIC). Environmental Guidelines. Retrieved September 3, 2015. http://www.conservationwiki. com/wiki/Environmental_Guidelines
Binns, C. (2006). The Shocking Truth Behind Static Electricity. Retrieved September 7, 2015, from http://www.livescience.com/4077-shocking-truth-static-electricity.html
Guldbeck, P., & MacLeish, A. (1985). The care of antiques and historical collections (2nd ed.). Nashville, Tenn.: AASLH Press.
Heimerdinger, G. (2011). How Moisture and Humidity Affect Installation of Wood Floors. FCI Magazine. http://www.lignomatusa.com/wp-content/uploads/2013/05/FCI-Jan-Feb.pdf
National Information Standards Organization. Environmental Guidelines for the Storage of Paper Records. Technical Report NISO-TR01-1995. Ogden, S. Temperature, Relative Humidity, Light, and Air Quality: Basic Guidelines for Preservation. Northeast Document Conservation Center. Retrieved September 6, 2015, from https://www.nedcc.org/free-resources/preservation-leaflets/2.-the-environment/2.1- temperature,-relative-humidity,-light,-and-air-quality-basic-guidelines-for-preservation
Smithsonian Museum Conservation Institute. Furniture Care and Handling. Retrieved September 6, 2015, from http://www.si.edu/mci/downloads/taking_care/MCIFurnitureCare.pdf
Smithsonian Museum Conservation Institute. Caring for your Paintings. Retrieved September 6, 2015, from http://www.si.edu/mci/english/learn_more/taking_care/care_painting.html
Wine Guardian. Wine Cellar Environmental Control Systems. (2013, September 12). Retrieved September 3, 2015.