5 Steps to Concrete Finishing

Merely pouring concrete for a basement slab or sidewalk is easy; concrete finishing, on the other hand, requires a certain degree of finesse and skill. However, with the right tools, a willingness to get a little dirty, and the following information, anyone successfully finish their own concrete.  

Use a Bow Float to Flatten the Slab

If a slab is too big to reach out to the middle of without walking on it, one first must run a bow float over the top of the concrete. A bow float is a tool that has a long extendable handle attached to a broad flat piece of metal around 3 feet long. The bow float smoothes out the concrete by forcing the large rocks down and drawing the water and finer concrete particles to the top. This water mixed with fine concrete is often referred to as, “cream.” A bow float can be extended out to great lengths and works best while the concrete is still fairly wet and goopy. If the area of the project is fairly small, wait for the concrete to set up a little and try using a mag float instead.

Use a Mag Float to Draw Up Moisture

As concrete stiffens a mag float will be needed to fine tune the smoothing job which is usually begun with a bow float. The term mag float is short for magnesium float, and is so named because the flat part of the tool is made out of magnesium. One of the unique properties of magnesium, and what makes it especially useful for this type of work, is that it draws water to the surface of concrete. Scrubbing the surface of drying concrete with a mag float will pull a good deal of cream to the top. If using this type of float, always begin with the edges of the slab and work inwards. If a slab is so wide it’s impossible to reach the middle portion without walking on it, people generally put on a pair of knee boards and slowly shuffle out to the middle on their knees. The knee boards should disperse any body weight and keep the concrete from denting.

Use a Trowel to Fill any Gaps and Finish the Surface

If a slab has a good deal of cream that has been worked to the surface with a mag float, a trowel can be used to smooth the concrete to its finished state. A trowel used for this purpose should be pressed flat against the concrete, but have modest pressure added to the back end of the trowel as it is worked back and forth over the surface. For example, if swiping the trowel to the left, one should add pressure to the right-hand side of the trowel. By doing this, the back end of the trowel will act as a razor edge smoothing the concrete and filling any gaps, voids or pocket that may have formed in the slab. Running a trowel back and forth over the entire slab will give a flat polished finish to the concrete.

Use a Broom if More Traction is Desired

In some public areas such as sidewalks or driveways, more traction is desired. To give the concrete a rough texture rather than a polished finish, one must scrub the surface with an industrial broom, right after smoothing it with a trowel. The bristles of a broom leave behind a row pattern that is much less slippery than polished concrete.

Use a Concrete Sealer

If a concrete project has fully cured, a sealer may be applied to make the concrete more water and crack resistant. It is imperative that the concrete be fully cured before applying a sealer so that moisture is not sealed within the slab. If this happens, the slab will never fully dry in the middle and be structurally unsound.