All the conservation labs/workshops have mylar or melinex as the most commonly used material while treatment procedures as well as in packaging and safe storage or display etc. Such widely and frequently used material is known to all by these trade names (Mylar and Melinex), but not many know the exact properties and actual name of this material. The actual name is Biaxially-oriented polyethylene terephthalate (BoPET).
The properties that attract its use in conservation are:
- it has excellent clarity
- it has extreme smoothness when there are no additives
- much less permeable to gases
- it reflects up to 90% of light, including much of IR spectrum
There are many types and grades of Mylar. Mylar that should be used for conservation and preservation is Mylar D or Melinex 516.
The BoPET film must not contain any plasticiser, surface coatings, UV inhibitors, or adsorbents and be guaranteed to be non-yellowing with natural aging.
Following are good references to know more about Mylar/Melinex use in conservation and their preferred type.