The Concrete Polishing Process

Concrete surfaces can be luminous and appealing or dull and boring. Inside, many people choose to cover concrete floors with wood, tiling or carpet. Others know that a little work can produce luxurious results.

It might require borrowing, renting or purchasing the correct equipment: A floor polisher with a diameter of at least 15 inches; a edging polishing tool that’s either handheld or made to walk behind; broom; pump sprayer; epoxy filler for cracks and wide joints; a chemical hardener to give a lacquer sheen; and a wide variety of diamond-style abrasive papers that are sized to fit your grinder attachments. These attachments should range from very course at no more than 20-grit to very fine at 3,000-grit.

There are two ways to ensure a successful concrete polishing: in a wet or dry method. Use paper appropriate for the method you’ll be performing. If using the wet method, ensure the floor is wet at all times, which will keep your paper from overheating and keep airborne particles to a minimum. The dry method, however, is known to be faster.

The first thing that must be done is to inspect and prepare the surface, removing with a diamond grinder any uneven areas and sealants, paints or glues. After this is finished, seal levelly all visible cracking with an epoxy filler of the same color as the floor.

A rough diamond grinder is then needed to fully smooth the floor after the epoxy dries in the cracks. Most experts start with a two or three passes with a rough, metal-bonded abrasive attachment of about 40-grit, then progress to a few passes each with finer abrasives of about 80-grit then 150-grit. For concrete floors that are already fairly smooth, a few passes with fine-grit abrasives might be all that’s needed.

The concrete surface is now ready to be thickened or “densified.” This requires a hardening chemical made of liquid silicate that bonds with the concrete to create a much smoother and impenetrable surface. The liquid should be spread over the floor with a broom then left to dry for at least a half-hour. A squeegee will then remove any excess liquid and lightly smooth the surface. Follow the manufacturer’s instructions for details on how long to let the hardener cure before proceeding to the final polishing.

The grinder now is ready to employ finer resin-bonded abrasives to polish the densified concrete. Start with a pass of 100-grit then move up by exponentially — 200, 400, ect. You’re finished when the floor is sparkling to your satisfaction. Some proceed all the way to a 3,000-grit resin-bonded attachment for an ultra high sheen. The goal is to replace, or “lap,” the previous grit pattern with each successive grit. To get at the edges and in corners, it will be necessary to stop the grinder between each paper replacement to hand-polish where there grinder can’t reach.

This doesn’t mean the work is done, though. Many end their concrete finishing job by using a product to protect their concrete from oil and chemical staining, as well as the accumulation of dirt and grease. Store-bought stain-guards are typically applied with a pump sprayer similar to those used to fertilize grass and should be re-applied every few months for optimum results.

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is a blogger and DIY home improvement expert, who enjoys writing about all things construction, including concrete polishing techniques.

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