Pollutants

Museums are faced with the unavoidable problem of pollutants. Everything
held in the Museum has the potential to be a pollutant. Just as objects
evaporate moisture, the materials of an object’s construction may also
evaporate pollutants.

Gaseous pollutants are created by a process called off-gassing. This is an evaporation of volatile chemicals from materials. The best defense for determining if something is off-gassing is your nose. If you can smell something, the material is releasing pollutants. An example is new car smell, that smell is all the new materials in the car off-gassing into a closed environment. Another example is a cedar chest, they may be great at keeping moths out of your clothes, but the wood itself can also can damage sensitive items. If clothes are left in a cedar chest for too long, many types of cotton will yellow and break down and deteriorate caused by the evaporation of gases from that particular wood.

The difficult part of this equation is that the object itself may be off-gassing. It is important to consider materials that you store your objects in, bad choices can lead to damage and in some cases destroying objects. For centuries, many museums displayed objects in beautiful regal oak cabinets, but it turned out this was the worst choice, as oak is one of the worst offenders when it comes to off-gassing. It is best to choose an inert material, often labeled as archival or acid-free. Common mistakes are made when people store things in cardboard boxes (a cheaply made and highly-acidic material) that causes long term irreversible damage. Off-gassing is also compounded by the presence of high humidity, so a stable environment will help minimize the potential for damage.

The other types of pollutants found in Museums are particulate. This includes dust and other particles in the air. Textiles are very vulnerable to the affects of dust, as the humidity changes in the environment, the fibers of a textile may expand and contract allowing dust particles to get caught between the fibers. The dust then acts as small microscopic daggers damaging the textile. Dust and particulates are also great food source for pests. The best defense for particulate pollutants is good housekeeping.

Examples

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Adhesive damage: Never attempt to repair an objects on your own. Many tapes and adhesives available are not archival and often highly acidic causing worse damage if used for repair.

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Bubble wrap damage: Bubble wrap may be great packing material, but it is not good for long term storage. This plastic in the bubble wrap broke down and left a residue on the object

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Bynes Disease: This shell is suffering from what is called “Bynes Disease,” it not actually a disease, but an efflorescence of salts on the surface of the shell caused by the off-gassing of the wood case where it was being stored.  As the oak off-gassed into the closed drawers, the salts within the calcium carbonate structure of the shell “break out” and create an efflorescence on the shell, causing irreversible damaging to the shell.