Lewis bag

A Lewis bag is a thick canvas pouch that ice is loaded into and then struck with a wooden mallet to break it down into crushed or pebble-sized pieces, a technique used for drinks like a Mint Julep or a Swizzle that call for finely crushed ice rather than cubes.

The canvas material is the key detail, since it absorbs meltwater created by the impact of crushing instead of letting it pool with the ice, which keeps the finished crushed ice drier and slower to clump than ice crushed in a plastic bag or blender. It also muffles the noise of crushing compared to hitting ice directly against a hard surface.

A good bag is made of heavy, tightly woven canvas that will not tear or leak fibers into the ice after repeated use. It should be rinsed and fully air dried between uses so it does not develop mildew while damp. A common mistake is overfilling the bag, which makes it harder to crush the ice evenly and increases the risk of the canvas splitting under a hard swing.