What’s the difference between polished concrete and a grind and seal?

If you are interested in exposed aggregate concrete flooring for your business or home, the term ‘polished concrete’ is usually bandied around.   It can be extremely confusing, especially when even builders and contractors misuse the terminology.  This can and does, often, lead to a grind and seal being installed, instead of a mechanical polish (which is the correct terminology for a true polish) and often a grind and seal is not the finish they hoped for.

If planned for, and done properly, a mechanical polish is a great flooring solution if an exposed aggregate look is what you are after.   Due to their initial similar appearance, many customers are not aware of the differences between polished concrete and ground & sealed concrete floors. This can result in confusion when requesting quotes or gathering information for your project and disappointment with the end result.

Polished concrete & sealed concrete look similar, but they are quite different

Polished concrete and ground and sealed concrete floors can look almost identical to the untrained eye.   Even some inexperienced contractors may have trouble first distinguishing between the two systems. However, the shine/finish is achieved by completely different processes. Polished concrete is more labor intensive and involves more steps than grind/sealed concrete floors.

Here’s a quick summary of comparing the two processes: Concrete polishing is the mechanical process of polishing the surface of an existing concrete slab using engineered floor grinders fitted with industrial diamonds. During this process, the concrete is honed and polished using progressively finer grits of diamond abrasives until the floor reaches the desired level of shine (either level 1-4; matte to high gloss).

However with a ground and sealed concrete, the gloss is achieved from a topical sealer. The process is simpler, involves less steps and is a much more basic finish.   In terms of durability and benefits, a true polish has a much longer lifetime expectancy and is much more durable, especially in areas with high traffic. We typically only recommend ground & sealed concrete as a more affordable alternative to polished concrete in commercial projects where a more rustic, basic finish is required – we usually do not recommend this finish for a residential home or environment where a quality look and feel is required

In contrast, a grind and seal finish involves grinding the concrete to a certain level and then applying a topical coating over the surface. This coating can be made of various materials, such as epoxy, polyurethane, or acrylic, and provides a protective layer that sits on top of the concrete.

A grind and seal is quite a basic finish, and due to the thousands of micropores that appear after the grinding process, the topical sealer will find its way into these pores and, like grout, trap dirt, which is very difficult to clean. We generally don’t recommend a grind and seal for residential homes for this reason.

Keep reading to learn about the key differences of concrete polishing vs grind and sealed concrete floors, including appearance, durability, and price difference, to help make your decision for your next decorative concrete flooring project.

What are polished concrete floors?

Polished concrete is the mechanical process of honing and polishing the surface of an existing concrete slab using engineered floor grinders fitted with industrial diamond abrasives. During this process, the concrete is ground, honed, and polished using finer grits of diamond abrasives until the floor reaches the desired level of shine. With polished concrete, there are four levels of finish/shine.

Different levels of polished concrete

Level 1 – Soft Matte Finish: a Level 1 Polished Concrete floor has a matte finish and will appear soft and hazy with minimal clarity or reflection.

Level 2 – Low Sheen Finish: a Level 2 Polished Concrete floor has a low luster sheen. This is the most popular floor finish for polished concrete. At about a 100 feet distance, you can start to see slight overhead reflection.

Level 3 – Medium Gloss Finish: a Level 3 Polished Concrete floor has a medium gloss finish. This polish produces a gloss on the floor that will clearly reflect objects. This finish is popular in areas where a glossy finish is desired, i.e. restaurants, breweries, retail, etc. There will be good light reflectivity. At about a 30-50 ft distance, the floor will clearly reflect light.

Level 4 – High Gloss Finish: a Level 4 Polished Concrete floor has a high gloss finish. This polish produces the highest level of shine, similar to glass with high light reflectivity. The floor almost appears wet from many vantage points.

What are ground and sealed concrete floors?

Grind and sealed concrete is exactly like its name. The process involves grinding your concrete, then sealing with a topical sealer.

Here are the steps for grind and seal concrete:

1. The process involves grinding the concrete with engineered concrete floor surface grinders to remove any contaminants from the existing slab.
2. Next, cracks and divots in the floor are patched with patching material as necessary.
3. Depending on the project (i.e. desired finish and durability requirements), the concrete may be ground again with finer diamonds to further smooth the floor. If the concrete is soft, porous or free of contaminants, a second pass may not be necessary.
4. Afterwards, the surface is vacuumed and dust extracted with industrial grade equipment 
5. Lastly, your sealed concrete floor is sealed with a topical sealer. Depending on your requirements, and your space, your concrete flooring company will recommend the best type of sealer for your project. Softer, more porous concrete may require multiple additional coats of sealer.

Now that we’ve defined both polished concrete and sealed concrete floors, let’s breakdown the main factors of their differences, including appearance, durability, lifetime, and cost.

Polished concrete vs a grind and seal

1. Appearance

Sometimes it may be hard for the inexperienced eye to spot the difference between polished concrete and sealed concrete because they can look almost identical. Both polished and grind/seal concrete floors can have a matte, satin, or gloss appearance. However, the finish (either matte, satin, or gloss) is achieved in unique processes. For polished concrete, the concrete is polished using finer grits of diamond abrasives until the floor reaches the desired level of shine (level 1-4). However with sealed concrete, the finish is achieved from a topical sealer.

Another appearance difference is grind/sealed concrete has a more consistent appearance from one concrete floor to the next. The reason is the high-performance sealer is consistent on each application because it is not reliant on the concrete’s profile, unlike polished concrete. This may be beneficial for those looking to match sealed concrete floors throughout their space. With polished concrete, the finished look can vary from concrete to concrete because a different canvas is presented and extraneous factors can affect the final finish, such as the level of hardness or imperfections.

2. Durability

When choosing between polished concrete and grind/seal concrete, it’s important for your flooring contractor to understand your project’s space and desired level of durability and what is going on in the space.   Is it an area with traffic (i.e. foot traffic? Is the area prone to spills?

Polished concrete offers long-term durability and includes benefits of densifying, hardening, and dust-proofing. This system is recommended in high volume spaces because it has a scratch-resistant finish and requires minimal maintenance. It also lasts for decades when properly maintained. However with ground and sealed concrete and depending on the traffic level, your surface may need to be resealed annually. For larger spaces, this can ultimately be more expensive than polished concrete.

3. Cost

A mechanical polish is more labor intensive and costs about double that of a grind/seal. It is very important that customers understand the differences as well as their builder, concreter and/or architect to ensure that the finish intended is the finish supplied.

Do you want to explore polished concrete/concrete overlays for your next project?

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