All About Polishing
Concreate uses a predictable, historically proven technique of concrete polishing. However, that doesn’t mean we’re stuck in our ways! We are happy to adapt and evolve with improving technology. In the end, all we care about is doing the best looking, longest lasting, and most quality job possible. Let’s get into it!
Polishing Concrete: The First Steps
Any existing floor finish (Epoxy, VCT, or Carpet for instance) that is currently on the concrete will need to be removed. That means removing both the surface material and adhesive bonding it to the concrete. We’ll get this done by using a mechanical floor prep machine that uses metal abrasive diamond pads in combination with stripping chemicals if needed. If the aggregate (stone) in the concrete is to be exposed, the very top cream layer of concrete that exists from the original pour will need to be removed as well. This process requires the use of more aggressive diamond tooling to achieve the desired look. It’s a little more complex than most people realize!
There are many different types of polished concrete finishes, but we will focus on the most common polishing process. The polishing process includes very specific steps. But the most important thing to understand is that every concrete slab is different, with unique characteristics and needs. The exact steps to achieve the look a customer wants can vary greatly depending on the concrete slab itself.
The Right Tooling
Before the concrete polishing process begins, Concreate conducts a floor hardness test to determine which diamond tooling we should start with. Metal diamonds come in varying levels of hardness. That means if the concrete is super hard (5-7,000 psi) then an extra soft diamond pad is used to start the process. For concrete that is extremely soft, it would require an extra hard metal diamond pad. Once the proper tooling has been determined, we begin the concrete polishing process.
After selecting the proper tooling, we examine the concrete surface for needed repairs. Once cracks and holes have been cleaned out, they are filled and ground down to level. We’ll also fill any joints, if needed.
We’ll start hitting the surface with one of the following grits: 6 – 14/16 – 30 – 70 – 120. When trying to expose aggregate (stone) in the concrete, you have to start at a lower grit to remove enough of the surface concrete to uncover the stone. We typically end metal-bond diamond abrasive grinding using our 70 metal diamonds unless we plan to grout the floor. (If the concrete is porous, we’ll never get the gloss we want, so that’s a good indication that the floor needs to be grouted. We also always prefer to grout if we are trying to expose aggregate in the floor.) In this instance we would do a second pass of 70 metals, 120 metals, or even a 50 grit transitional diamond, depending on the needs of the floor, to cut the grout off.
Our next cut could be another pass of 70 metals, 120 metals, or even a 50 grit transitional diamond depending on the needs of the floor.
After we complete the initial grinding process using our metal diamonds, we use a 50 grit transitional diamond pad. This pad helps in the transition between the metal diamonds and the resin diamonds. It also helps remove any remaining scratches. New slabs that have had no finish put on them can often start at this step since we polish wet, and our cuts tend to be a little more aggressive than those who polish dry.
Honing, Applying Stains and Densifier
So once the metal-bond diamonds are completed, we begin using our 50 grit transitional and continue progressing using the 100 then 200 grit. This process is called honing. On larger, wide-open projects, we can also move to using a ride-on power trowel to help speed up production.
If applying stains, we apply them after we complete the 200 grit resin step. We’ve been known to stain and densify after our 400 grit as well. Densifying and staining is part of knowing how to polish concrete and, while not hard, can be disastrous if not done correctly. Different manufacturers of stains and densifiers often have their own preferred methods of application, so you need to know the material you are working with and how to achieve the best results.
After the stain has dried (If using concrete stain) we apply the concrete densifier, keeping the slab wet anywhere from 20-30 minutes. Grinding removes a thin layer of concrete, so the concrete itself becomes weak and soft. Applying a concrete densifier will help harden the concrete once again and shrink the size of the pores in the surface of the concrete. Sometimes a second coat of concrete densifier is used. While this is how to polish concrete, everyone does it a little differently.
After our concrete stain and densifier have completely dried, (It’s important for the concrete to be completely dry!) we continue the concrete polishing process using our 400 grit diamond pads. It’s usually during this step of the concrete polishing process that you will begin to see a glossy floor.
Polishing The Concrete
Once we complete the 400 grit process, we can continue and finish the polishing process depending on the amount of gloss our customer wants. If the customer wants something utilitarian and super easy to maintain, we can stop after the 400 grit. However, our resin grit diamond pads get increasingly finer, so if our customer wants a mirror like finish, we’ll continue all the way to 3000 grit!
We end the concrete polishing process with polishing pads on a burnisher and apply different kinds of sealers depending on the needs of the customer and performance of the floor. This will give the concrete its ultimate shine, and help protect the floor from staining, discoloring, and under performing.
Step-By-Step Concrete Polishing Process
- Complete hardness test.
- Repair any cracks and holes.
- Fill joints.
- Grind the concrete using 14/16 – 30 – 70 – or 120 grit diamonds. Grout if the floor is porous or has voids from exposing aggregate.
- Complete the grinding and start the honing process using 50, 100, and 200 grit transitional pads.
- Apply stains and densifiers.
- Continue honing with 400 grit pads and polish with 800, 1,500, and 3,000 grit resin pads.
- Complete the concrete polishing process using a burnisher with diamond polishing pads and appropriate sealers.
Contact Concreate about Concrete Polishing!
This is how we polish concrete at Concreate. We hope you found it informative, but if you have any questions, don’t hesitate to give us a ring or send us a message on our Facebook page. We’re here to help!
If you’re interested in working with us, get in touch using the form below: