Concrete Polishing

The following blog will cover proper concrete polishing. I have been polishing terrazzo and concrete for many years and have been trained by HTC and I am certified by RetroPlate as a RetroPlate densifier installer.
Concrete polishing was born out of terrazzo polishing. As far as I can tell it was started by HTC at the request of a box company who wanted a shinny concrete finish,
Polished concrete is a low dust, low maintenance floor that will never need replaced. It can also be very beautiful when done right.
The most important aspect of concrete polishing is a proper pre-inspection along with a hardness test and mock up.
During the initial walk through pay particular attention to nails, bolts, pipes and studs that are above floor level and on the floor. These will need cut before grinding. One stud and render an 850 Pound grinder useless. If one of the heads is bent you will not be able to use the grinder until it receives expensive repairs. Also look for holes in the concrete. while they may not be very evident on an unpolished floor, when the floor is polished, they will fill with dust and will break up the shine. In short they will be much easier to spot.
Also look for Coating on the floor. any coatings may cost additional days to a job.
Always warn that the floor will most likely have level problems between expansion joints. This can and will cause larger exposed aggregate at the joint lines. This is the result of a flatter floor.
Warn that different pours may give different results. Not all concrete will be equal. Last, but not least, understand the expectation of your customer. If you are polishing a factory, they may want a low dust, low maintenance floor, but not care about a few scratches. A showroom may require a perfect shine.
When doing the initial scratch, hardness test one should scratch several areas. I remember a house we did in polished concrete, We went in and scratched five areas. We did not bother to test the bedrooms which were covered by carpet, Upon arriving at the home to polish the concrete we discovered the bedrooms had a lot of damage, including significant cap loss. The cap is the top of the concrete which is flat. When there is cap loss it will take a significant amount of grinding to eliminate.
At Safe Dry we use HTC grinders. For the mock ups we prefer to use the 500. It is smaller and easy to set up and get started. The 500 is also the grinder of choice for residential work. The 800 will, in most cases, do a better job, but its 32 inch cut and 480 volt power requirement make it to problematic.
One of the toughest decision may be what grit to start with. It is easier to start at 40 or 80 and go down to a lower grit if need be. The problem is you may be several hours into the job before you realize you made a mistake. When grinding you can start with 40 grit metal bond diamonds and go up to 150 grit metal, than down to 100 grit resin bond, or you can go up to 80 grit metal then use 80 grit mixed resin diamonds. then use 100 grit mixed resin. If you use a lithium based densifier now is the time to densify. Then use 200 grit, 400 grit, 800 grit, 1500 grit and 3000 grit for a high shine.
This blog is meant for professional floor polishers only. There are hundreds of problems that can arise while polishing a floor. The only thing you have to rely on is experience. If you have little or none, then you WILL fail.
If you would like Safe Dry to give you a quote just give us a call at 877.824.0501 or log onto http://www.safedry.com/concrete_polishing.html