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Wet vs. Dry Grinding and Polishing: What You Need To Know

There is more to concrete grinding than taking a big machine to a floor. In fact, there are two distinct methods with different advantages and disadvantages. These involve grinding dry and grinding wet.

All contractors will have different opinions on both methods and will have a preference for either one, depending on the specific situation. 

Concrete grinding and polishing have firmly planted themselves as effective and economical methods to strengthen and beautify concrete surfaces. Installed professionally, ground and polished floors can enhance surfaces for years. They are environmentally friendly, low-maintenance, and sustainable.

The two primary methods of polishing, “wet” and “dry”, both have their own reasons as to when and why they should be used. It is critical that the correct method is chosen to achieve the best results. In this article, we will discuss the advantages and disadvantages of each and where they should be used.

What is concrete grinding and polishing?

During the process of grinding and polishing, rough surfaces are smoothed to improve appearance. This is done using heavy machinery and discs that resemble sandpaper. It is a multi-step process, the final one being polishing. Throughout the process, the discs used may change and by the end, very fine ones are used to achieve that “polished” look and feel.

There are many benefits to having a polished concrete floor, including:

  • Durability: Polishing a concrete floor increases its hardness and, hence, makes it more durable than regular floors. This is especially useful in high-traffic areas as they are capable of withstanding it. Higher durability also means that the floor is much harder to damage.

  • Easily maintainable: A polished and ground concrete floor is easy to maintain. Cleaning is as simple as sweeping and mopping the floor.

  • Cost-effective: Due to their high resilience to foot traffic, polished concrete floors will only need renewing every seven to ten years in high-traffic areas. This makes it very cost-effective when compared with other aesthetically-pleasing surfaces.

  • Sustainable: Due to the methods used to achieve a polished concrete floor, virtually no waste is left behind. Additionally, floors that receive this treatment exhibit reduced mould and dust.

What is the difference between wet and dry grinding and polishing?

Dry grinding and polishing
When dry polishing, commercial-scale polishing machines and tools specialised in refining concrete are used to grind the surface of a concrete floor. These are used to achieve the desired shine. It is often in dry polishing to incorporate diamond discs with coarse diamond grit at an earlier stage, then an even finer disc is used for the final polish.

There are machines available today that were specifically designed with the dry polishing process in mind. Concrete floor grinders and polishers are often paired with dust extraction systems, or industrial vacuums, to capture any dust that is generated during the process.

Wet grinding and polishing
Wet polishing involves keeping the diamond abrasives at standard temperatures and any dust that is produced is captured in a “slurry” state. This can often help in dust control, however, the final finish of the floor rarely exhibits the same shine that can be achieved with dry polishing.

Wet Grinding and Polishing Advantages

  • Extends the life of diamond tools: Wet grinding and polishing can help increase the lifespan of diamond tooling due to this method keeping the diamond tools much cooler. This means they do not glaze over and can grind more aggressively for longer. On harder floors, this allows the diamond to cut faster.

  • Effortlessly removes unappealing scratches: The water involved in wet grinding helps remove any imperfections left in the surface by the initial stages of the process.

  • A dust-free environment: Wet grinding and polishing produces no airborne dust, meaning that dust collectors, respirators, and vacuum cleaners are not necessary, reducing operating costs. The water also shields the user from toxic silicon particles.

  • A deeper understanding: Wet grinding was developed long before dry grinding and so contractors tend to be drawn to it.

  • Versatility: There are many flooring materials that are compatible with wet polishing including porcelain, marble, terrazzo, quartz, limestone, travertine, and many types of granite.

  • Generally less expensive: Usually, wet pads incur lower costs than dry pads. Water also helps keep the pads from overheating so machinery has an extended lifespan.

Wet Grinding and Polishing Disadvantages

  • Produces waste: When a large surface is concerned, a considerable amount of water is required. This may not be the most appropriate choice when dry grinding can be used.

  • Low gloss level: It can be difficult to replicate the shine that can be achieved with a dry polish when wet polishing. This means that it may not be the most suitable option if the desired finish is a premium shine.

  • It often results in a mess: Although wet grinding reduces dust exposure, it can produce a “slurry” that requires a lot of cleaning to remove. This can cause further issues as it is often difficult to dispose of.

  • The process is longer: Wet grinding often takes longer than dry grinding, depending on the contractor, this can lead to higher costs for the client. To achieve a moisture-free substrate, the floor must be dried for several days before it can be coated.

Dry Grinding and Polishing Pros

  • Enhances the surface shine: When compared with wet polishing, dry polishing yields a glossier, shinier finish, increasing light reflection.

  • A soft concrete floor would benefit: When polishing a soft concrete floor, dry polishing is more effective. Polishing wet causes the diamonds to grind aggressively, causing gouge marks.

  • Faster, cleaner work: Wet grinding has long working times and leaves a difficult cleaning job at the end. Dry grinding is much quicker and easier to clean. Since it is dry, it also allows for any coating to be applied immediately after vacuuming.

  • Quick turnaround: Dry grinding allows you to see results immediately. Workers find that they have an easier time assessing their work and making any necessary improvements. 

  • Maintenance is simple: Dry grinding machines usually require less maintenance as the bearings are not exposed to wet conditions, which cause rusting and wearing out.

Dry Grinding and Polishing Cons

  • Dangerous conditions: There are more health risks associated with dry grinding due to the large amount of dust produced. Keeping this under control is key to preventing respiratory health problems.

  • Additional costs: Dry grinding can be more costly due to the requirement of dust collectors, vacuums, and respirators.

  • Glazing poses a risk: If an inappropriate tool is used, overheating can occur, causing glazing. This can also be caused by dry grinding on very hard concrete.

What is the greener method?

Which method is greener is still up for debate. The lack of sludge when dry grinding is ideal for addressing the issue of disposal more effectively. The regulations for disposing of slurry vary all around the world, so it is important to consult the regulations specific to your jurisdiction before you decide on how to dispose of it.

One of the primary concerns regarding wet grinding is the presence of toxic silicon. During the wet polishing process, dust clouds, which are typical of the dry polishing process, are removed. This dust contains substantial amounts of silicon, posing a large problem for the flooring industry. Even with the most advanced dust extractors, the dry process can still result in dust exposure.

Which environments are most ideal for concrete grinding and polishing services?

In addition to industrial and commercial buildings, concrete grinding is perfect for a wide variety of flooring applications. It is most commonly used in the following places:

  • Hospitals
  • Manufacturing plants
  • Showrooms
  • Schools/Universities
  • Warehouses

Wet or dry grinding: What is the better option?

This is the most common question within the concrete polishing industry. Both methods have reasons for and against in different situations, there is no singular answer than can be given. Important factors to consider when making the decision are your budget, your preferences, and the amount of time available.

There are situations where one method must be used such as in the food and beverage industry where it must be dust-free. In this case, the wet polish technique is needed. Dry polishing is better suited in other businesses that seek high-gloss floors and where they would like to impress their clients. Depending on the situation, a balance of both is recommended.

When concerned with very hard concrete, wet grinding should be used first followed by dry grinding. Wet grinding and polishing dry is a good method for achieving a high shine as it will expose aggregate and remove a significant layer.

Conclusion: Consult The Professionals

It is imperative to hire a contractor who is experienced in grinding and polishing concrete if you are unfamiliar with the overall process. Having damaged flooring will not only ruin the look of your flooring, but it can also be very expensive to have it repaired. Keep your floors updated by professionals, not inexperienced individuals.

In any case, an experienced contractor is a requirement if you are unfamiliar with the overall process yourself. Damaging the floor will not only ruin its appearance but it can also be extremely expensive to repair it. Ensure that your floors are maintained by professionals.


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