Guidelines for “Display Cases”

Here’s a quote from one of the articles “Here Today, Gone Tomorrow?”, by By Dana Wegner, Curator of ship models, Department of the Navy, Naval Surface Warfare Center:

Quote: Guidelines for “Display Cases”
A few words are due on the subject of “display cases”. Make sure the model is mounted firmly on a base that is large and strong enough to protect it when it is moved or repaired. Keep the model and “display case” away from sources of direct heat, cold, vibration, humidity, and sunlight. Avoid exposing the model to rapid changes in temperature and humidity. And be sure the air in the display case can change once or twice daily, for the reason I explain next.

All things deteriorate at some rate, and some things deteriorate faster than others. Even a well-built model will deteriorate more quickly if it is kept in an adverse environment. Environmental conditions can retard or accelerate the rate of deterioration. For example, a newspaper placed in sunlight turns yellow faster than a newspaper kept in a file drawer. When things deteriorate or change chemically, they release molecules into the air in a process museum conservators call “off-gassing.” When you can smell paint or glue, whether it is wet or supposedly dry, you are smelling the off-gassing of those products. Usually the smell diminishes considerably or seems, according to your nose, to stop altogether. Nevertheless, each material still off-gasses as it undergoes inherent chemical changes, or as it changes because of heat, time, humidity, or light. One easy way to tell if your model is off-gassing is to smell it. If it is more than a few months old and still smells like glue or paint, either something has not dried yet, or something is inherently unstable. If the model or the inside of the “display case” smells like vinegar, serious decomposition is likely taking place.

Insignificant as these weak gasses seem, when a ship model is placed in a microenvironment where the air does not move much, like in a “display case”, the gasses become relatively concentrated and may begin interacting in various and unpredictable ways with the materials with which the model and case were made. Much of the interaction between off-gasses and particular materials is harmless, but some can be perilous. Think of a “display case” as a heatless cooker that will bake a model and anything else within its walls.

Model builders can help retard deterioration by allowing a little free air into the display case. Air inside even loosely fitted display cases can be one hundred times more stagnant than the air in the surrounding room. The air in the exhibit case should exchange at least once or twice a day. A 1-inch diameter hole will allow a cubic yard of air to exchange naturally daily. So, a 1-inch hole is sufficient to ventilate an exhibit case with an interior of 36 by 36 by 36 inches. Of course, many modelers display their work without exhibit cases, and if you are willing to accept some mechanical breakage, that is fine. However, frequent dusting then becomes necessary, because dust, when combined with humidity in the air, will form a concrete-like coating that is difficult to remove, even with solvents.

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