Preserving Our History: Barrier Films vs. The Bugs

By Patrick Kelley, ACE

In a museum setting, wrapping or bagging objects in a protective film is commonly done for several different reasons:

Sensitive Objects: If a sensitive museum object is being stored closely to other items known to be infested, a protective film will keep the insects out and prevent pests from infesting that particular piece.

Infested Objects: If a certain object on exhibit or in storage if found to be infested, the first thing that can be done to prevent the spread of the infestation is to “bag” the object in a protective film. In this circumstance, the procedure would keep the pests inside the bag until an appropriate treatment could be performed.

Freezing Treatments: Prior to freezing an object that is suspected to have pests, objects are wrapped to maintain humidity levels before and after freezing.

Anoxic Treatments: For low oxygen treatments, objects must be completely sealed with a barrier film that does not allow the passage of oxygen in or out. Some museums will even store certain objects for years in an oxygen free environment within a barrier film.

Question: What are the best films that can do the above tasks while keeping pests from penetrating at the same time? Below are some of the choices:

1. Polyethylene films having a thickness of >10 mil work well for short or long term storage. Polyethylene alone cannot be used as an oxygen barrier. You can see from the photo image above that the thinner PE films are easily penetrated. This is also generally the cheapest alternative.

2. Polyester films work well as a barrier for insects and oxygen. Polyester films are those films that use Polyethylene terephthalate or (PET). These can have the brand names of Terphane®, Melinex®, Hosta-phan® or Mylar D® (Note: Mylar
D is no longer being manufactured by Du Pont). These can safely be used for long term storage.

3. Aluminized barrier films such as the brand name Marvelseal 360® or U.S. military specification packaging (MIL-PRF-131K-Class I) are extremely pest resistant and can also be used in anoxic treatments.

4. Ceramic coated transparent barrier films such as the brand names, Escal® and SuperEscal® (puncture resistant) are also extremely insect resistant and can be used in anoxic treatments.

It is important to keep in mind that certain plastics can adversely affect collection materials. Plasticizers or other compounds can migrate to the surface of some types of plastic and eventually damage the objects that they are touching. Stay away from plastic films using poly vinyl chloride (PVC), polyvinylidene chloride (PVDC, better known as Saran® Wrap) or cellulose diacetate.

Information regarding the interaction between flexible films and art/collection objects was generously supplied by Éléonore Kissel, In Extenso…Paris, France.

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