To mix overlay materials for a small- to moderately-sized project (2,500 square feet or less), I use several 30-gallon drums as the mixing vessels because they are large enough to accommodate two to three bags of material. Determine the volume of water required per bag and then put all water in the clean bucket first.
Always add the exact amount of water specified by the manufacturer. Adding too much will give you a mix that’s too soupy, and adding too little will make the material too stiff to self-level properly.
It’s a good idea to prewet the bucket so dry material does not accumulate on the sides. Be sure to dump out any residual water before putting the required amount in for mixing. Once the premeasured water is in the bucket, you can add the dry overlay mix while simultaneously mixing with a power drill fitted with a mixing paddle. Self-leveling overlays generally required three to four minutes of mixing time.
And for larger jobs...
To mix materials for larger jobs, you can still use buckets, but you’ll need more of them, as well as more personnel for mixing and pouring. On one 7,000-square-foot project, I had five mixing buckets going simultaneously, mixing at one-minute intervals. Working in this fashion enabled us to pour almost continuously, expediting the job.
For mixing materials, I recommend using a top-vented industrial drill running at a minimum of 650 rpm, but avoid mixing at too high a speed, or you could end up whipping unwanted air into the mix. Always have a backup drill in case your primary drill burns out. There are numerous types of mixing paddle available. My favorite paddle for mixing self-leveling overlays is similar in shape to a football.
On large commercial projects, it’s often more efficient to use a grout-type continuous mixing pump with an attached hose for placing the overlay. As a backup in case of pump failure, be sure to keep two or three mixing buckets and drills on hand. When using a pump, you usually must prime the delivery hose with enough water or slurry made of cement and water. There are also prepackaged materials specifically for priming pump hoses. Make sure you have a bucket or vessel at the end of the hose to capture the slurry so it won’t contaminate the floor surface.
Applying topical color
If you intend to stain or dye your overlay, read the manufacturer’s technical data sheets for do’s and don’ts. Some overlays set rapidly, permitting stains or dyes to be applied just several hours after overlay placement. Others may need to set overnight. Some manufacturers recommend light sanding or screening, using a buffing machine with sanding pads or screen affixed to it, before applying topical color to ensure good penetration and full color development.
Always experiment with a representative jobsite mockup so you know precisely how the stains, dyes, or tints you intend to use will take. This will help you avoid any unexpected surprises.