From: dlzc1@cox.net   
      
   Dear Bret Cahill:   
      
   On Wednesday, May 11, 2016 at 3:59:26 PM UTC-7, Bret Cahill wrote:   
   ...   
   > Actually I'm looking for a thin flexible elastic film   
   > that has low permeability to gas.   
      
   Unobtainium.  As you stretch the film, to alter and *always* increase the gas   
   permeability.  One, you make the film thinner, and two, you break   
   intermolecular bonds from "relaxed" natural state.   
      
   ...   
   > One of interest is the old Saran cling wrap,   
   > polyvinylidene chloride:  With an ultimate yield strain   
   > of 20% it is 4X stretchier than Mylar yet has a   
   > permeability an order of magnitude lower than Mylar.   
      
   How about rinsing the film after stretch in shape, with some sodium or   
   potassium silicate?  You may have to expose the film to corona to get this to   
   stick... Are the final contents moist, or very dry?   
      
   David A. Smith   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)