Should the side that's shiny on one side be up or down?
Many cooking resources say that when cooking with aluminum foil, the shiny side should be down, facing the food, and the dull side up.The shiny side will reflect more of the heat than the dull side.
Some newer sources say that the shiny side should be down, since it doesn't make a difference which side of the foil faces up.
What Einstein Told His Cook and America's Test Kitchen both say that it doesn't make a difference in cooking.You can either cook or freeze food with aluminum foil.
There is a dull side to aluminum foil.It matters which side is used up or down according to many people.It doesn't make a difference.The manufacturing process causes the two sides to look different.The side that comes in contact with the rollers is shiny when the sheets of aluminum are rolled out.
The shiny side makes no difference.It reiterates that foil has a shiny side and a dull side.It wasn't very informative.
The shiny side of aluminum foil will be more reflective than the dull side.The explanations seem to indicate that the shiny and dull sides are simply a by-product of the manufacturing process.The claim is not supported by the explanation.What is the truth?
The shiny side of aluminum foil is not as shiny as the dull side.The difference is so small that it won't make a difference in cooking.It's probably more efficient to cook with the dull side out than it is to say that there is no effect.There should be little discernable change in cooking times when measured over time in high temperatures.This may seem like a lot of explanation to come to the same conclusion, but it is not my purpose to give inaccurate explanations.
There are three basic ways heat can be transferred.Conduction is the transfer of heat from one object to another.When we cook on the stove, this is what happens.
The transfer of heat is accomplished by the movement of liquid or gas.Radio waves, microwaves, and X-rays are radiation.The heat energy is being carried from one surface to another.
Any object with a temperature above absolute zero emits heat.The heated coil, sides, and rack in your oven are emitting energy.The food and the vessel emit this energy.
The major source of cooking heat is the oven.The food is being cooked in the oven.Don't be confused by "convection ovens", they use a fan to make the oven more efficient.The heat in an oven is transferred through invisible light rays.
A shiny surface will make a difference to radiation.Waves reflect on shiny surfaces.One side of the foil is more shiny than the other because it is smooth and has less flaws.The shiny surface of the foil should reflect more radiation than the dull surface, which will allow it to trap waves rather than reflect them back.The major source of heat transfer should not be affected.
A baked potato is a good idea.When baking potatoes, you should place the dull side out.In the long time it takes to bake a potato, either side will work the same.The potato will be cooked through steam when the energy from the foil is transferred to the potato.
A bigger difference may be made by how tightly the potato is wrapped.The air trapped in the aluminum foil pouch may slow the transfer of heat.Wrap your potatoes tightly.
Since I mentioned the manufacture of foil through the explanations, I should write more about how foil is made.
The manufacturing of aluminum foil is similar to making pasta at home.A large block of almost pure aluminum is rolled through giant steel rollers and spread out to make it longer.There are lubrications added to the operation.The thickness is reduced at each pass through the rollers.Once foil thickness is reached, the large flat sheet is split into different lengths.
This may seem simple, but the process can be difficult.As the aluminum is rolled out, it gets hotter.It can stick to the rollers if it heats up too much.