The shiny and dull sides of aluminum foil result from its manufacturing process:
Production Method: Foil is made by rolling aluminum sheets between heavy rollers. During the final pass, two layers are rolled simultaneously, causing the outer surfaces to contact the polished rollers (creating the shiny side) and the inner surfaces to matte against each other (dull side).
No Functional Difference: Both sides have identical heat conduction and cooking properties. The U.S. Aluminum Association confirms the reflectivity difference is negligible (≤1%).
Common Myths: Misconceptions suggest the shiny side should face food or heat sources for better reflection, but studies show no practical impact on cooking results.
Usage Tip: For convenience, use the dull side (less glare) to wrap food when visibility matters. Otherwise, either side works equally well.
In short, the appearance is a byproduct of production, not a design feature. Focus on foil thickness and quality rather than side orientation for cooking success.
