Cold storage is recommended for especially vulnerable materials. Original prints, negatives, and transparencies (not glass plates, daguerreotypes, ambrotypes, tintypes, or other images on glass or metal) should be placed in packaging (archival folders in board boxes in double freezer weight Ziplock bags) in cold storage, and temperatures should be maintained at 1.7-4.4”C (35-40 °F). According to the guideline of National Archives facilities, clear plastic bags such as Zip-locks or flush-cut bags with twist-ties (polyethylene or polypropylene plastic bags) and cotton gloves are needed.