Art owners packing antique paintings for shipping are mostly concerned with their physical safety. Indeed, improper handling or an inadequately insulated package can damage an artwork irreversibly, and these risks require proper precautions. Yet, an invisible risk that often goes unnoticed is the impact of abrupt temperature and humidity fluctuations. To minimize this risk, professionals may rely on a 24-hour acclimatization period for artwork.
Differential Movement: A Major Cause of Damage
One of the primary mechanisms of artwork damage is differential movement between its component parts. Canvas, wooden stretchers, animal-glue sizing, and gesso all respond to moisture in the surrounding environment at different rates. The paint film above them, especially aged oil paint, responds differently to these changes. As a result, differential movement can occur when the support repeatedly contracts and expands, while the paint layer may lose adhesion to the underlying surface, causing cracks, cupping, and delamination.
Temperature changes can make the process more complicated in several ways. They can affect the relative humidity (RH) inside a sealed space, even when the absolute moisture content remains unchanged. As a result, a crate sealed in a studio at 50% RH may have a different RH level after reaching its destination. Cold temperatures can also make aged paint and natural varnish more brittle, meaning that an impact a painting might tolerate at normal temperatures could cause damage when the materials are cold.
How Packing Antique Paintings for Shipping Can Minimize Damage
The main protective strategy when packing antique paintings for shipping is to slow the rate of environmental change, as it cannot always be prevented entirely. A crate lined with a foil-laminate moisture barrier and equipped with conditioned silica gel can help buffer changes in humidity during transit. Small data loggers placed inside the crate are also useful for recording temperature and RH levels, allowing the receiving party to review environmental conditions throughout the journey.
The 24-Hour Acclimatization Rule
Regardless of the crate design and other protective measures used to keep artwork safe during transportation, allowing sufficient time for acclimatization is an important precaution. If a cold crate is brought into a warm room and opened immediately, moisture from the warmer air can condense on cold surfaces, potentially including the artwork. That’s why professionals may recommend keeping the crate closed for at least 24 hours at the destination, although the acclimatization period may be extended to 48 hours in some circumstances. This allows the contents to gradually adjust to the surrounding temperature before the crate is opened.
A similar principle applies when artwork is brought from a climate-controlled storage facility into a packing room. It may need time to acclimatize to the temperature and humidity of the workshop before packing, helping minimize the risk of condensation and environmental stress