Good morning Leah,
As the acting C2C Care community monitor, I'd like to thank you for posting this question to the community! As it happens, I did a lot of research on low-density polyethylene for my master's thesis.
100% virgin Low-density polyethylene (LDPE) is chemically inert; however, additives (e.g., plasticizers, UV inhibitors, surface coatings) added by the manufacturer during production often go undisclosed. These additives can release VOC's, be detrimental to objects they come in contact with, and can shorten the usable lifetime of the plastic film. The usable lifetime of LDPE has been reported to be 5-10 years in a museum environment; exposure to UV and light can cause chemical degradation such as discoloration and embrittlement. Heat also causes LDPE to degrade and although the plastic film will most likely not be exposed to extreme heat in the museum storage environment, it was heated to its melting point during processing.
If the covers from Bestauto are intended for indoor/outdoor use, they likely contain light stabilizers/UV inhibitors, which change the chemical properties of LDPE. These include carbon black, benzophenones, benzotriazoles, salicylates, and hindered amine light stabilizers. Could any of these additives have an adverse effect on the vehicles?
Do your due diligence - Get as much information as you can from the supplier and/or manufacturer, and test the materials before committing to long-term use.
As always, if anyone in the community has experience, advice, or resources to share, please do!
Additional resources:
Products Used in Preventive Conservation contains a critical review of plastic films most commonly used in storage, display and transportation.
Yvonne Shashoua's book
Conservation of plastics: materials science, degradation and preservation (2008) provides a deeper dive on the causes and mechanisms LDPE degradation.
Safe Plastics and Fabrics for Exhibit and Storage - NPS Conserve O Gram 18/2Polyethylene - Cameo
Protective packaging: an introduction to the materials... - recommends product testing and provides brief description of simple test methods (I have pdf if needed)
VOC emissions from plastic materials used for storing and displaying heritage objects - ICOM-CC conference paper (I have pdf if needed)
Testing materials for use in the storage and display of antiquities: a revised methodology - presents a revised Oddy test method (I have pdf if needed)
The Use of A-D Strips for screening conservation and exhibit materials - simple testing method to detect acidic off-gassing in the range of pH 5.4-3.8.
Materials Testing - AIC Wiki
Revs Institute - may be worth contacting their preservation staff for cover recommendations.
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Sharon Fickeissen
Connecting to Collections Care Monitor
Senior Library Conservation Technician
Hagley Museum & Library
Wilmington DE
sfickeissen@hagley.org------------------------------
Original Message:
Sent: 12-01-2022 16:58
From: Leah Craig
Subject: Vehicle Car Covers
We are looking for car covers for long-term storage for our vehicle collection. We would ideally like to use something clear. We are looking at a Bestauto brand car cover made of low-density polyethylene plastic. Would this be safe for long-term use, or are there dangers of off-gassing? Do others have experience with vehicle covers for vehicles in your artifact collection?
Thank You,