Many homeowners opt for exposed concrete floors in their homes because they can be attractive and easy to clean.
Before you can add a colored stain followed by a coating of epoxy, urethane or wax to make a floor shine cement, it is necessary to prepare the floor surface. A professional swab or sander equipped with an abrasive disc can remove any existing paint, stains, discoloration or small imperfections from the floor surface.
Need for equipment
Rent a polisher or a professional floor sander. You will need coarse, fine, and superfine sandpaper discs that fit under the polisher, depending on the amount of sanding required for the job. Purchase duct tape and plastic sheets to cover furniture, fixtures, and walls. Make sure you have goggles and more dust masks, as concrete dust is bad for the respiratory system.
Before you start sanding, remove all furniture from the room. Sweep or vacuum the floor to remove debris.
If you are indoors, install plastic sheeting to protect walls or furniture from dust generated by the sander. You will place the sanding discs under the polisher, one at a time.
Follow the instructions to connect the disk to your machines; the accessory will depend on the type of machine used. Some remain in place alone.
The right things
The choice of sandpaper depends on how much sanding needs to be done.
Choose coarse sandpaper, in the range of 40 to 60, for sanding and base removal. For smooth finishes and the removal of small imperfections, use 80 to 120 grit sandpaper.
For the smoother finish use superfine sandpaper, 200 to 400 or higher. If you use wet, dry sandpaper, you can wet the area before working to contain the dust.
Do not let the slurry dry on the concrete as it will harden in place. If you only have a small area to sand, you can also use a hand sander, orbital sander, or belt sander. Coarse imperfections may require the use of a special diamond disc and a sander for concrete floors.
Start in a corner with the sander, working in sections of about 1 square meter.
Methodically work the entire length and width of the room. Clean the dust area with a broom and dustpan after you’re done.
After the first pass, go over the floor with a disk of fine or superfine sandpaper to finish the surface. Examine the concrete floor to make sure you have removed any paint, stains or other coatings.
Repeat the sanding if necessary until smoothing is complete. Scrub the area and let it dry completely before applying stains or finish coats.