Does it make any difference when you wrap food with aluminum foil for grilling or baking or making a steam pouch whether you put the shiny side in or the shiny side out?

I've seen at least one answer to a questiong about grilling that made mention of this.

4 Answers 4


I've been told that the shiny side should go on the inside for cooking, and the outside for freezing. In other words, do you want to reflect the heat into the food, or away from the food?

However, common sense (which fails very often) tells me that with the temperature ranges involved, any benefit is marginal, if it exists at all.

The only time it might matter, is if you were trying to warm something up in the sun. Then it might make a difference.

EDIT: From The Straight Dope:

The truth is that the shiny side is not treated with a dangerous chemical. Mineral oil is used as a lubricant during the rolling process, some trace of which may remain on the finished foil--but it's not dangerous. The shiny side is shiny because of the way foil is made. During the last pass through the rolling mill, a double thickness of foil is run between the rollers. The side of each sheet that comes in contact with the polished steel rollers comes out shiny. The other side has a matte finish.



The official word from the Reynolds aluminum people is as follows: "It makes little difference which side of the Reynolds Wrap aluminum foil you use--both sides do the same fine job of cooking, freezing, and storing food. There is a slight difference in the reflectivity of the two sides, but it is so slight that laboratory instruments are required to measure it."

  • 1
    This is what I've been told. A nagging voice in the back of my head says: 'But if it doesn't really matter, wouldn't companies selling this foil go for the cheaper production method (presumably) of having identical sides to the foil?' Jul 22, 2010 at 13:43
  • 13
    See edit. The shiny/dull side IS the cheaper method. Jul 22, 2010 at 13:51
  • 3
    Also, even if it wasn't, public perception would play a role. Plenty of people think it matters.
    – ceejayoz
    Jul 22, 2010 at 14:34

I just cooked 12 baked potatoes; 6 shiny side out, and 6 shiny side in. Each potato was individually wrapped and all potatoes were about the same size. I cooked the shiny side out potatoes first, then turned off the oven and left the oven door open for 30 minutes before cooking the other six. I also unwrapped both sets of potatoes after sitting for five minutes out of the oven, sliced them in half and put butter in between. Both baked at 375°F for an hour timed by the oven; they cooked exactly the same. Neither was more done than the other nor had more crispy skin.

  • 1
    This sounds like a fair experimental method. Unfortunately, it's buried inside too much anecdote & too little formatting, making it a very difficult read.
    – Tetsujin
    Sep 22, 2019 at 11:11

I think with the foil's shiny side outside the food cooks a bit later because it reflects heat away from the food


It takes longer to bake with the shiny side out, I know this because i have cooked for years for large numbers of people and have to do it in about 2 hours max. Shiny side in cooks things faster.

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