If you own or collect art, then you must consider the environmental conditions in which you house your artworks to avoid damage to the media and supports. In particular, the temperature and humidity levels are crucial factors in caring for artworks. Two questions we are often asked are: “How do temperature and humidity affect my paintings?” and “What temperature and humidity levels are ideal for my art?”

The answers vary. First, take into account the media you want to protect. Do you have oil paintings, acrylic paintings, works on paper, or gilt frames? Each material reacts differently to environmental changes. The answers also depend on the season and location of your art: they would be different for someone whose collection is in New York than for one in California or Hawaii. What all artworks need, however, is a stable environment.

When you assess plans to control the environment of your artworks, consider both the impacts of temperature and humidity as distinct elements and the impacts of the interplay between them. Extreme temperature and humidity or fluctuations in their levels damage paintings and frames because their multiple layers expand and contract as moisture spreads into or out of the surrounding air. The layers vary in how they swell and shrink: their components expand and contract at different temperatures and soak up moisture at different rates.

Temperature and Humidity Threats to Your Paintings:

Canvas becomes loose when the air is humid and it is exposed to moisture. It then tightens when the air dries out. Excessive expansion and contraction of the canvas causes it to slacken and eventually sag on the stretcher, requiring either keying out or re-stretching. A painting is healthiest when taut. Over-tightening a weakened canvas in hot weather, however, can cause further damage. When the air becomes cooler, the canvas may tear as a result of the increased strain imposed upon it by moisture deposits. More rapid damage can result from quick changes in atmospheric conditions, as when a sensitive canvas is hung in a room heated by steam radiators, which quickly lose their heat when the steam is shut off. The constant movement of the canvas and continuous readjustments that occur in the paint layer can accelerate deterioration.

Panel paintings—that is, pictures painted on wood—react differently to humidity depending on the type and cut of the wood. All wood, though, expands as it absorbs moisture due to impregnated water trapped within the fibers of the wood. The resulting structural damage to panel paintings includes warping, splitting, and breaking of the wood panel support. The wooden substrate of frames is susceptible to the same risks.