Can Burnishing Sometimes Be the Better Finish? | Concrete Decor
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Can Burnishing Sometimes Be the Better Finish?

It is easy to understand the benefits of polished concrete — they are listed on everyone’s brochures. The word about polished concrete is out and we have done a great job of promoting the industry. Polished concrete is growing. Great pictures of very well-done projects are all over the Internet. The marketing has been great and many contractors are jumping on board. And the consumers are seeing a great product.

Along with this growth, something else has happened — polished concrete is evolving.

We have taken what was originally a full mechanically polished concrete system (six-plus steps) and started changing it. The term “polished concrete” has become a term that describes a flooring system family with its own subcategories. I do not see this as a bad thing. We have adapted to the needs of clients and designed different “forms” or “categories” of polished concrete. I have accepted this evolution of our industry and believe it is a good thing. I now view polished concrete as more than a “one system fits all” approach. It is a moving and evolving system that is adapting to different environments.

I can imagine your scowling face as you read this and wonder, “What the heck is this junk?” But just think for a moment about all the projects you bid last year and lost. With some of them, someone simply underbid you to install the specified system. But what about those where the general contractor or architect wanted polished concrete but did not specify any one system? Others bid against you — and their bid specified offered a very different system then yours did. They offered a resin polish, a hybrid polish or even a burnish and called it polished concrete. This is real and it is happening.

I have been a stringent full mechanical polished concrete purist since the late 1990s. I never accepted any other form of polished concrete besides a full six-plus-step polish. Now in today’s market I have realized polished concrete has outgrown that idea. Please do not get me wrong —I still 100 percent believe that a full mechanical polish is the best and truest form of polishing. But I find it difficult to force my ideals on every client.

Many clients want polished concrete, but quite frankly cannot afford it every time and in every situation. What do you do? Do you bend the truth (and man, is there a lot of bending going on) and tell them you can do it for less and then cut out three steps and pile on the guard? Or do you prefer to educate your client about concrete polishing?

I recognize that a full mechanical polish may not fit every client’s needs or, more likely, their budget. So let’s explore some options. These options are types or subcategories of polished concrete, but they are not the true form of polished concrete and their benefits and aesthetics are different. Burnished concrete and diamond-burnished concrete are two categories I run into a lot.

To start, we need a definition of true mechanically polished concrete. Polished concrete is the altering of a concrete surface by processing it with grinding, honing and polishing techniques. These techniques utilize diamond-bonded abrasives to mechanically reduce the peaks and valleys of the concrete surface. In combination with concrete densifying, coloring and sealing (or the application of a polishing guard), these methods are designed to achieve the following effects: resistance to damage from water and surface abrasion, increased surface hardness, an increase in coefficient of friction, increased light reflectivity, reduction in concrete dusting, and reduction in maintenance. Mechanically polished concrete also produces a very aesthetically appealing flooring system.

Now that we have a working definition of true polished concrete, we can compare it to burnished concrete and diamond-burnished concrete.

Burnished concrete is a system that utilizes a high-speed burnisher that spins at approximately 1,500 rpm to 2,500 rpm. The goal of the burnisher is to heat, melt and buff a chemical product that has been applied to the surface. This action fills the small pores in the concrete with the applied chemical by melting and dispersing the product. In the maintenance industry, the chemical of choice is typically a form of a wax-based product. In the polishing industry the chemical is a densifier product. Sometimes the densifier is followed with a guard product for additional shine and stain protection.

While burnishers are mechanical and spin under power, that is the only similarity they have to a concrete grinder/polisher. While burnishers spin at a very high rpm and an aggressive pad may be capable of scratching the surface, there is no true series of pads and not enough down pressure to process the concrete. The typical black, red, white or hogshair pads used to burnish are not designed to process concrete. They are deigned to melt and buff a topical coating.

If a densifier is used, the surface will acquire the benefits the densifier provides and will also have a glossy appearance. But burnished concrete will not have the properties of a processed concrete surface that has been grinded, honed and polished — specifically, the mechanical reduction of the concrete surface’s microscopic peaks and valleys, clarity, ease of maintenance, additional flatness, and longevity. On top of these factors, burnished concrete does not look nearly as attractive as a mechanically polished concrete surface.

Burnishing with diamond-impregnated pads add yet another dimension to this. The same burnisher is used, but a pad with a sprayed-on diamond and resin mixture is utilized. This diamond-impregnated pad is typically available from 400 grit to 3,000 grit, so you can do multiple steps of diamond burnishing with a powered, rotary machine. When this is done with a concrete densifier you have a system using progressively finer diamond-bonded abrasives. You also enjoy the benefits that a concrete densifier provides.

Mechanical grinding with diamond tooling, densifier and multiple steps sounds like concrete polishing, but you still have a system with no down pressure and one that spins at too much rpm to do any real grinding.

Diamond pad burnishing affects the very top layer of the cream and has very little impact on reducing the peaks and valleys of the concrete surface. There is not enough weight to create a deep enough scratch pattern to thoroughly abrade the surface, especially if the FF (floor flatness) of the surface is poor. Starting at 400 grit, there is no chance of anything besides a cream type of polish. A basic salt-and-pepper appearance is out of the question with diamond pad burnishing.

While true mechanical concrete polishing can tighten and process the surface to create a shine even without densifier, diamond pad burnishing needs the help of a chemical to create a form of a topical chemical polish. There is some concrete processing happening but compared to true mechanical polishing, very little.

Different categories or forms of polished concrete may be hard to accept and agree with. They are even more difficult to explain. I think we need to start with understanding that our market is changing. Polished concrete is adapting to fit the needs of clients and, unfortunately, their bank accounts. By being able to understand and explain the different forms of polished concrete we can offer our clients different solutions. These solutions are not equal to the high standards to which we hold true mechanically polished concrete. But they do fall under the category of polished concrete. Most importantly, they are options for a client who does not want her floor to be covered by carpet and epoxy.

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