Sealed and Densified Floors
Many people do not know the difference between sealed and densified
floors… and the difference is huge! Both will stop dust, but the similarities stop there.
Densifiers are used to finish or harden concrete. It is often applied right after the slab is cured or hard enough. It soaks into the concrete 90% and leaves only about 10% on the top. Many in the concrete industry say to truly densify a floor, it should be applied a second time after 30 days. Some even say it should be applied again after a year unless you’re polishing the floor, in which case densifier is added during the polishing process 1 or 2 times. A double densified concrete floor should partially bead water but will not be waterproof. Therefore, oils will still be able to penetrate. A small amount of visible sheen may be seen, but a sheen will be almost non-detectable. The densifier penetrates 90% into the slab, therefore will not get worn off unless the slab gets worn down.
The term sealer is often used to describe any clear coating that is applied over a concrete or masonry surface. Here, we are explaining acrylic sealers used for coating and protecting concrete floors or exterior slabs. Acrylic sealers get applied to a slab after it has cured for 30 days. There are many water-based clear acrylic sealers with different solids contents that range from 7% to 60% solids. The lower the solids percentage, the less protection you get. We like to use xylene-based acrylic sealers whenever possible with a 40% or higher solids content. A xylene/solvent-based sealer penetrates deeper into the concrete and re-wets itself on later applications ensuring a good bond even years later. A high solids acrylic sealer protects the floor from oil and water fairly well. Acrylic sealer is often used and works well as a finish coat over stained concrete.