Acid Wash vs. Broom Finish

Broom Finish

• A broom finish is a simple and inexpensive procedure used to treat the surface of concrete to add texture and traction when it dries. After the concrete is poured and the bleed water is allowed to evaporate, the concrete technician uses a specially made broom to smooth over the surface. Some technicians first smooth the concrete with a trowel. The broom's bristles make a grooved pattern in the concrete that, when dried, becomes a rough surface.

Acid Wash

• You can also acid-wash your concrete to add texture, although the process is more commonly used to treat concrete so it can be painted, covered or stained. The acid used in acid washing is muriatic acid, another name for hydrochloric acid (HCl), a highly corrosive chemical that will etch the concrete, which roughens the surface of the concrete to allow a coating to better adhere to it. Generally, this procedure is done to newer concrete, but if the concrete is several months old, you must first wash it to remove particles that will not be affected by the acid.

Acid Stain

• Do not confuse acid washing with acid staining. While both procedures use muriatic acid to treat concrete, they serve very different functions. Acid washing treats concrete to be coated, while acid staining uses chemicals to add color to the surface. The result of an acid stain is an abrasive-resistant coating that takes on a variety of colors and patterns that fuse into the concrete. Some of the colors available from acid staining include black, green, reddish-brown or tan.

Uses

• The most common uses of a broom finish on concrete is for outdoor walkways; many sidewalks are made with a broom finish. Pre-manufactured slabs of broom-finished concrete are also available from some manufacturers. Treating acid with concrete is more extensive and complicated because it uses caustic chemicals. You must use caution to not damage vegetation surrounding the area or to pollute any nearby water sources with acid/water runoff.