The wearing surface of a concrete floor is no more than one inch thick. And yet the workmanship and materials that go into its construction will determine the strength and life of the floor. A floor that is properly finished will hold up under extremely severe conditions indefinitely. It will resist "dusting," and if made of a non-porous concrete will resist acids and brine solutions. The first step in a safe procedure for finishing floors is to advise the ready mix producer precisely how the concrete is to be used and ask for his recommendations. He will prepare a mixture suitable for the type of floor that is to be constructed. The two things that then require close attention in obtaining a good floor finish are the base and the wearing surface. Base concrete for floors placed on the ground level of a building is a mixture of not more than 6 to 6 and one half gallons of water per sack of cement. It should be brought to grade not less than one inch below the proposed finish level. When it has partially hardened, it should be brushed with a stiff broom. Besides cleaning the surface, this scores it to provide mechanical bond. The base should be wet-cured for at least 5 days; for at least 2 days if high early strength concrete is used. The surface should be protected from grease, dirt, and paint during the curing process. Power floating and troweling are essential operations for a good floor finish.