Melting Plastic

courtesy, Frankie Hayden

shelving unit, post-burn: courtesy, Frankie Hayden

PlasticComparisonLast week our C2C team conducted our 4th fire recovery workshop. The Western Carteret Fire & EMS station executed a controlled burn of the mock museum we had previously installed in their training building. Although plastic (polypropylene) storage boxes have made it through previous controlled burns just fine, this time one completely melted. In one of our earlier burn tests, plastic boxes protected the contents as well as microchamber boxes and better than regular archival boxes. However, we have always placed them at the low or mid level of shelving areas. This time we were more deliberate about a control and test for plastic placement. We staged 4 similarly sized boxes (2 cardboard and 2 plastic) with nearly identical contents. Each contained a book, a shell, a small crocheted textile, a wooden figurine, a copper vessel, a brass vessel, a slate writing board, and a record disk. BoardBoxfromTopThe fire chief on duty estimated that the fire reached a temperature of 800 degrees Fahrenheit, somewhat hotter than past controlled burns, which were recorded at 700 degrees. The fire destroyed both the cardboard and the plastic boxes on the top shelf, although the charred cardboard retained much of its form (see right). The plastic box melted and wound up as a glob with shimmery strings dangling down. The same box on the lower shelf came through the burn intact, with a layer of soot on the outside. [See above right for a direct comparison of the two boxes that were identical before the fire.]





What about the objects the boxes contained? Most–including wood, metal, and textiles–were covered in soot and ash but could still be salvaged with much conservation work. The plastic items inside the boxes (a record disk and a frame for a small print), however,also melted. Globs of melted plastic adhered to some of the materials, but in most cases, could be pried loose. Objects in both the cardboard and the plastic boxes were not well protected from the fire on the top shelf. In contrast, the same boxes 3 shelves below protected their contents just fine from the film of soot and ash that covered all surfaces. PlasticMelt2Are plastic boxes a bad choice for disaster mitigation? No. They do offer protection from leaks and pests and on lower levels of shelving, present little additional fire risk. On upper shelves they are more likely to melt and pose a greater risk to artifacts. However, at a heat intense enough to cause melting, all artifacts will be severely damaged, regardless of container type. Melted globs of plastic will add to a salvaged object’s conservation needs. These globs may come from other objects as well as from melted polyethylene foam that is a standard shelf liner in most museum storage areas. Above is a view of the foam liner residue, which melts into a brown lacy layer, and the melted remainder of the lid and sides of the plastic box. Upcoming posts will address additional aspects of this workshop including the Incident Command System, the simple triage system we used, and rapid treatment techniques we practiced.


About collectionsconversations

This blog will contain posts from the C2C project staff on a variety of topics related to collections care and disaster preparedness. Enjoy the posts and let us know if you would like additional information or have a topic you would like for us to address.

Posted on June 10, 2014, in Connecting to Collections, CREST, disaster preparedness, fire, workshops and tagged , , , . Bookmark the permalink. Leave a comment.

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