Aluminum Foil: Shiny Side Out or Dull Side Out? What's the Difference?

Aluminum foil is a go-to kitchen essential for many when grilling, using the oven, or for insulation and dust protection. But what's the right way to use it? Should the shiny side or the dull side face out? And how can you prevent fish from sticking? Let's dive into the best ways to use aluminum foil. Due to the manufacturing process, aluminum foil is made by passing two layers of foil through a final rolling mill. When separated, the side that comes into contact with the polished rollers becomes the shiny side. This often leads to confusion: which side should face outwards when using it? For grilling, the Taiwan Food and Drug Administration (TFDA) states that the cooking process relies "mainly on 'conduction' for heat transfer, not 'radiation'." Therefore, it makes little difference which side of the foil faces outwards. For non-grilling applications, many experts and chefs have traditionally recommended facing the "shiny side towards the food or baking pan." This is because the shiny side is thought to reflect heat, helping to cook and bake food more evenly. But does it really make that much of a difference? Dr. Chung Chi-yuen, an associate professor in the Department of Physics and Materials Science at City University of Hong Kong, explained in media interviews that the reflectivity of the shiny side is 88% and the dull side is 80%. While having the shiny side facing inwards can indeed speed up cooking, the effect is limited and the difference is negligible in everyday use. The food science website "culinarylore" also notes that "the shiny side is only slightly shinier than the dull side. While a small amount of energy will be reflected by the shiny side, it will not have a practical impact on cooking." So, stop stressing about it; using either side of aluminum foil for cooking won't cause any significant issues.