The COVID-19 crisis has raised questions that library and museum workers have never had to ask themselves before: How long does a virus last on materials? How can we mitigate exposure to staff and visitors? Is it safe to reopen? The REopening Archives, Libraries, and Museums (REALM) project aims to make these questions easier to answer. In Test 4 results, announced September 3, scientists found that COVID-19 is still detectable after six days on four common library materials when they are stacked: the covers of hardcover books (buckram cloth), the covers of softback books, DVD cases (polypropylene), and Mylar protective book cover jackets.