You know those hot sandwiches sold in grocery stores (northeast USA at least...) that are wrapped in a foil paper? Wouldn't it thermally make more sense to have the shiny foil facing in? To keep the heat reflected inside the sandwich?

1 Answer 1


The foil / paper lamination creates air pockets between the layers that retain heat. Also the paper side absorbs some moisture and oils to attempt to keep it from getting soggy

  • that's answer enough for me! Makes sense. I guess technically if there's a shiny side of the foil, even on the other side of the paper, this would still have a heat-retention effect huh
    – Trav
    Dec 19, 2020 at 15:53
  • 3
    You could add that both sides have essentially the same reflectivity for infrared radiaton (Pozzobon et al ).
    – M Juckes
    Jan 7, 2021 at 19:17

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