These jars are designed to house specimens stored in industrial methylated spirit. White opaque polyethylene bins are unsatisfactory because they become brittle and split open after a period of about 10 years, spilling alcohol into the storage area. Glass containers with synthetic seals increase curatorial maintenance work because over a period of 10-20 years the seals deteriorate. All-glass containers, on the other hand, have performed satisfactorily in reference for over 150 years.