CONCRETE COUNTERTOP POLISHING

by Nick Bertram, Concrete Countertop Specialties

Techniques and Tooling

Concrete countertops are a very hot item these days and fabricating them may be much easier than you think when you use the right tools and technique. This is definitely the key to eliminating frustration and ultimately producing a quality product.

I have found that a lot of the tooling that many concrete countertop fabricators are getting locally or via the internet, are not designed for use on concrete. I have extensively tested all varieties of tooling in the last three years and have been able to decipher which tools actually work well and which tools should stay in the granite world. Using the wrong tools for concrete polishing can adversely affect the quality of the countertops that you produce.

Pre-cast Polishing:

The tools needed for this are the Makita PW5001C, 5” Ultra Speed Pads, 5” Alpha Rigid Backer Pad, 5” Flexible Backer Pad, and an apron. Don’t overlook the apron, you will get wet! Polishing pads come in a series of grits that are as follows, 50, 100, 200, 400, 800, 1500, and 3000. If you are looking for the exposed aggregate look, I recommend using 5” Ultra Speed polishing pads starting at a 50 grit. If you are just polishing the crème, you will start with a 400 grit (very lightly). You will then work your way through the different grits until the desired look has been achieved. On some mixes, 1500 grit will be the last pad that you will use although others mixes will still continue to polish at a 3000 grit.

50-400 grit pads are actually grinding and removing material in preparation for the polishing stages. It is more cost effective and safer (because of the dust) to do these stages wet. You are removing material and working the pads very hard at this point and if there is no water to cool the resin in the pads, it turns soft and releases the diamonds. The 800-3000 grits are where the magic happens. If you are looking for a nice polish with a smooth feel, use the Ultra Speed pads for your top grits.

If you’re going for a super high sheen then running your 800 grit and up dry will pop a shine that many didn’t realize was achievable. At this point, the pads will not be removing any material therefore you will see little to no dust at all. The Hot pressed pads are by far the best dry pad for an ultra high shine.

Pour In Place Polishing:

It is easier and more cost effective to build pre-cast concrete countertops but occasionally, you or your customer will insist on having no seams at all and a pour in place application will be necessary. This is the only situation where I would recommend polishing dry all the way through your polishing steps and it wouldn’t be a bad idea to charge a little more to make up for additional tool wear and added headaches.

To do this, you will need the Makita 9565CV Polisher, 5”Hot Pressed Pads, a Pearl Vaccu Guard, and a 5” aluminum backer pad. Once again, you will need to decide whether you will be exposing aggregate or polishing the crème on top. The same grits mentioned for wet polishing will apply but not the same polishing pads. When polishing dry, the Hot Pressed Pads will be used all the way through the different stages of grits.

Now that we have the correct tooling covered, here are some tips and tricks to make your project come out the best that it can.

Surface Polishing

The key to flat polishing is keeping the head of your polisher flat and level with your top. Every time you tilt or dip your grinder, swirl marks could follow. I would recommend using a rigid backer pad for this because a flexible backer will allow your polishing pad to bend on the edges. Also keep in mind that just because the polisher has a handle, doesn’t mean that you have to use it. Try putting one hand on the head of the polisher, this will keep the weight in the middle of the pad instead of off to one side.

5” pads are better for top polishing than 4” pads. I know that this size difference is minimal but it helps a lot to go with a 5” pad because they give you a bigger base. It also doesn’t hurt that they cover more surface area and even though there is only 1” difference in diameter, you will finish quicker.

It depends on how much you want to spend on tooling but if your budget will allow it, definitely look into the DS-301 Planetary Polisher. It’s one of those machines where after you use it, you will ask yourself “how did I ever do this before?” It’s simple, the DS-301 will cover 12” in one pass instead of the 4 or 5 inches that you would cover with a single headed unit. Not only that but any problems of swirl marks go away because it has three points of contact which makes it almost impossible to not be flat on the surface.

Edge Polishing

Often times when I tell customers that they can polish their edges with a hand held polisher; they find it hard to believe. Think about it, granite fabricators polish edges all day, every day with the same polishers. Sure it is a bit harder to learn but once mastered, you will be polishing your edges in a fraction of the time that it took you to do with hand pads. Lose the hand pads for edge polishing!

If you have a radius edge that you want to polish, try a flexible backer pad. Just a little bit of flex in the backer will bend around your radius and eliminate lines that can occur from using a rigid backer. With that said, using a rigid backer on the flat edge will help you to stay flat the same way that it does when top polishing. For example, if you are attempting to polish a standard 3/8” round over; use a rigid backer on the flat edge underneath your round and a flexible backer for the actual radius. Move your polisher left and right across your edge. Do not roll it up and down; this will make your edge wavy.

This information should be a very useful guide on the correct tooling and techniques. However, this is a 101 instruction to Concrete countertop polishing. In addition to this, I highly recommend attending one of the many informative seminars that are available from companies such as, Concrete Countertop Institute, Decosup, and Brickform. Just like anything else, there are tricks of the trade and having someone teach you these things first hand can eliminate a lot of wasted time and money.

Most importantly, concrete countertop fabricators must always strive for perfection. Countertops differ from most concrete work that is done on a large scale. We are talking about a much smaller area that is in the most important room of any house and a lot closer to eye level. If you wouldn’t put the tops in your own home then your job isn’t done. The only thing that will limit you in concrete countertops is your imagination, so keep an open mind and don’t be afraid to try something new.

Check out the next issue of Concrete Decor where I will be writing about polishing under mount and integral sinks as well as edge profiling.

For more information and full line of tooling options, visit our website www.concretecountertopspecialties.com or give us a call at 866-902-7311.

Until next time,

Nick Bertram
Concrete Countertop Specialties
www.concretecountertopspecialties.com