There at least two reasons that will make aluminum foil smell bad.
Firstly, it is about oil contamination on its own. The oil contamination can be called the extra oil on surface of the aluminum foil which appears after rolling procession. These oils are dirty with complex components. They were thrown from the roll neck or the opening position of the machine, splashed and dripped on the foil surface. The harm of the oils which are on the surface of the aluminum foil is bigger than the other rolled materials. There are two reasons for this. On the one hand, most of the finalized aluminum foil must be with a cleaning surface as decorative and packaging material. On the other hand, it is of thin thickness on its own, which is easy to have bubbles when it is annealed. And oils will be formed into too much remains.
Secondly, it is about the printing. For examples, when we used aluminum foil as chocolate wrapper. Most customers ask for customized printing. To produce the one without any odor, we not only need to choose aluminum foil with high quality, but ask our factory to buy brand machine with high quality. One thing we can sure, as the vendor of Disney, our aluminum foil for chocolate wrapper is without odor, and can maintain the original flavor of food.