 Making flubber from polyvinyl acetate-based glues, such as Elmer's Glue, and borax is a common elementary-science demonstration.Borax, given the E number "E285", is used as a food additive, but is banned in some countries, such as the United States, China, and Thailand.As a consequence, certain foods, such as caviar, produced for sale in the United States contain higher levels of salt to assist preservation.