Simply put, polishing concrete involves using a series of diamond tools to grind, hone and polish the concrete surface. This is a common definition and while it may be technically accurate it does little to help the end user understand polished concrete. Below I have provided practical questions and answers to help the layman understand polished concrete.

Where Can I Use Polished Concrete?
Polished concrete is one of the most versatile flooring solutions available and can be used in residential, retail, commercial, institutional and industrial applications. There are two primary weaknesses that need to be considered when evaluating the use of polished concrete. The first is concrete’s permeability, which allows it to absorb potentially harmful substances like oil or solvents. The second weakness is its susceptibility to acidic substances, which will cause the cementitious portion of the concrete to breakdown and erode. Concrete densifiers and micro sealers offer protection against these issues but they are only suitable for non-industrial applications where mild exposure is experienced. The application of a chloride screen densifier is highly recommended in regions where the concrete may be exposed to deicing salt.

Environments that are primarily dry are ideal for polished concrete; incidental water exposure from outdoor foot or auto traffic is not a problem. 

What Constitutes a Good Polished Concrete Floor?
In a word, flat! Super flat floors are the gold standard whether we’re talking about a polished concrete floor in a warehouse or an aggregate exposed, stained and polished showroom. There are substantial benefits to the aesthetics and the safety of a floor that has been ground flat, they’re also easier to maintain and re-polish which means a lower cost of ownership. The polish should also be scratch free, poor quality polishes will have scratches and grinder marks in the floor. The final and most obvious signs of a good polish are clarity and gloss, you should see a nice clear polish with objects being clearly reflected in the floor. The polish should not look cloudy or hazy or have white patches.

How Do I Ensure I Get a Good Polished Concrete Floor?
You need to provide the bidding contractors with a proper process specification. I have provided a recommended spec below for tendering purposes. The worst thing you can do is not provide a specification because the concrete polishing industry is not regulated so contractors will price the cheapest possible system to win the bid and not necessarily the proper system or even an acceptable one. Once you have tendered your project with the correct specification you need to meet with the top three bidders to discuss their qualifications and experience. I highly recommend that you get at least two references where you can go and see the projects and speak to the customers.

The following outlines a proper concrete polishing process:

Nufinish SP1 Spec:
Flexible grinding head technology is strictly prohibited! Rigid grinding heads only. Adjustable grinding heads must be set on stiffest setting.

Step 1: Nufinish 35 grit metal bonded diamond. The floor is to be ground twice with the second grind to be performed in a perpendicular direction to the first grind.
* The floor must be ground flat at this step with no remaining low spots. 

Step 2: Nufinish 55 grit metal bonded diamond. The floor is to be ground once in a perpendicular direction to the preceding step.

Step 3: Nufinish 80 grit metal bonded diamond. The floor is to be ground once in a perpendicular direction to the preceding step.

Step 4: Nufinish 60 grit resin bonded diamond. The floor is to be ground once in a perpendicular direction to the preceding step.

Step 5: Nufinish 100 grit resin bonded diamond. The floor is to be ground once in a perpendicular direction to the preceding step.

Step 6: Nufinish 200 grit resin bonded diamond. The floor is to be ground once in a perpendicular direction to the preceding step.

Step 7: Densifier Application. A concrete densifier is to be applied to the floor carefully following the manufacturers recommended process.

Step 8: Nufinish 400 grit resin bonded diamond. The floor is to be ground once in a perpendicular direction to the preceding step.

Step 9: Nufinish 800 grit resin bonded diamond. The floor is to be ground once in a perpendicular direction to the preceding step.

Step 10: Nufinish 1500 grit resin bonded diamond. The floor is to be ground once in a perpendicular direction to the preceding step.

Step 11 (Optional): Apply micro-sealer and burnish. Beneficial for environments that may experience incidental exposure to liquids.
*The are no equivalents for the diamond tools used in this process, substitutions are not allowed.