when will aluminium foil float on water

The sole reason behind this is The principle of buoyancy. When The aluminum foil is Spread out flat, the weight of the foil is less than the weight of water displaced by the foil. It has a lighter density than water. However, when the same foil is rolled up into a ball, It becomes heavier, and the density increases. The weight of the ball becomes more than the weight of water eventually displaced by it. Therefore, it sinks