I feel ya' buddy ... we're all looking to beat the heat this month, some more than others. For those of you not safely ensconced in Hagley Library's delightfully air-conditioned reading room, stay safe and try not to dry out, seal together, or otherwise go the way of cellophane.
Cellophane was invented Jacques E. Brandenberger (1872-1954) in 1908 in Switzerland and was commercially produced there. In 1923, DuPont acquired U.S. patent rights, but it was soon revealed that water vapor could penetrate the film. This fact precluded its use for food packaging.
DuPont scientist William Hale Charch (1898-1958) resolved this problem, and in 1927 a patent was issued for the moisture-proofing system. Cellophane continued to be highly profitable through the 1950s, but by the 1960s new products began replacing it. Cellophane production declined through the 1970s and early 1980s with DuPont discontinuing it in 1986.
This circa 1957 advertisement is from Hagley Library's collection of E.I. du Pont de Nemours & Company Cellophane Division cellophane packaging photographs and sales materials (Accession 1995.254). This collection consists of undated photographs, one saleman's album, and one poster that all relate to cellophane packaging.