Floats are typically used to close up the concrete around the perimeter of a pour. Often, the perimeter of a slab is difficult to close up using a bullfloat and a hand float is required to float the concrete. Floats come in two main types, Magnesium & Wood. Magnesium leaves a smooth surface which essentially seals the surface similar to a bullfloat. A wood float leaves a coarse, open finish which helps bleedwater escape, this is especially useful when the mix does not contain any entrained air. Floating also helps bed the aggregate into the concrete providing more slurry (Cream) on the surface for finishing.