Polishing the surface of concrete cast into a mould is not new. In fact it's been around for some time now and concrete worktops and furniture are well known.
Traditionally to polish and piece of concrete SAFELY, fairly specialist equipment was required. I say safely because there are quite a few videos out there of people dry polishing concrete and creating a LOT of dust which is NOT good for your health. In fact concrete dust, where the sand or silica particles are effectively cut in to bit release crystalline dust which is considered to be the new asbestos! So dry polishing is a hard NO.
So the traditional method of polishing concrete safely would involve water and lots of it. It would involve using a wet polisher like the one in the image below;
Makita PW5000C - https://amzn.to/3Tyhvct
This bit of kit, which is great but pretty hardcore is attached to a hose and water is fed through the polishing pad. It does the job providing you're using the correct discs (see below) and creates a LOT of waste water. Gallons!
Because of the amount of water that is required the voltage of the tool is lower at 110V so requires a step-down transformer to power the machine like the one below;
The pads required are diamond infused and very specific to the job.
So this is what Chris (business partner) and I started out with years ago. We set our workshop up so that we had a mixing area to, well, mix the concrete, a moulding and casting area to build moulds and cast the concrete into and then a polishing area. As the polishing was such a wet process keeping it quarantined from the other areas was a must. So we needed space! And we need drainage which could take away the waste water/slurry.
Not ideal for a one-off project. So that's where the Etch & Clean System comes in.
What is the Etch & Clean System?
The Etch & Clean System is a fancy name admittedly for an etching solution coupled with a neutralising solution. It is specifically designed for use with PRECAST concrete where the concrete is poured into a smooth-based mould and the face of the concrete up against the smooth base (the bottom) is then polished up.
That's in contrast to Cast-In-Place concrete where the upper surface is finished using a trowel. The Etch & Clean System is not used in this process.
So back to PRECAST and the Etch & Clean System. The process is very simple and involves working the etching solution into the surface of the concrete and once its done its job a neutraliser is applied.
For any of you out there who have a basic knowledge of chemistry the following reaction takes place;
How Does It Actually Work?
To show you in action instead of me boring you with words you're better off watching a short video.
How does it work.. in words?
- Etch and Clean: The Etch & Clean solution is applied to the concrete surface and worked in using a circular motion. This process breaks up the laitance layer, a weak, thin layer that forms on the bottom face of the concrete in the mould.
- Neutralization: Once the laitance is removed, a neutralizing solution is applied to neutralize the acidic Etch & Clean solution. This step is crucial to make the acid safe (see chemical reaction above).
- Sand and Polish: With the laitance removed and the surface neutralised, you can now begin the sanding and polishing process. The Etch & Clean system makes this process significantly easier, allowing you to use a standard orbital sander instead of specialized concrete sanding, grinding, and polishing equipment.
QUICK QUESTION - why do I need to remove the laitance?
That is indeed a good question. When your concrete comes out of the mould the tendency is to give it a really light sand and even up the surface, job done. What you're effectively doing is blending the laitance layer but not removing it. Take off a bit here, a bit more there, that patch looks fine so I won't touch it. BOOM the surface looks great!
Well yes it does but the laitance layer has no structure and will scratch off easily and more importantly will scratch any sealer applied to it because it also prevents the sealer from really penetrating into the concrete.
So why choose the Etch & Clean System?
- Simplified process: As you can see the process is very simple and streamlines the sanding and polishing process, making it more accessible to DIY enthusiasts and professionals alike.
- Reduced equipment needs: By using a standard orbital sander, you can save on the cost and hassle of renting or purchasing specialised equipment.
- Safe: The Etch & Clean system results in inert and safe by products which means you're not harming your heath of the environment.
So in wrapping up, I hope you've found this article informative? If you have any questions then please email me at toby@concretelab.co.uk, give us a call or ping us a message on chat and we'll be happy to help!