I’ve lengthy cherished concrete flooring. I like their zero-maintenance enchantment, their industrial look that will get higher with time, and—although they work properly with radiant underfloor heating (see our Remodeling 101 on the subject)—I even like the sensation of a cool ground underfoot, particularly when temperatures rise.
However I’ve lately discovered a flaw in concrete flooring—one thing that had by no means occurred to me till I tried to remediate the state of affairs: In case your concrete flooring are stained, their colour is kind of actually “set.” In my condo, that’s an inconsistently utilized, dusty purple. If you wish to change it, you’ll must put in both main cash or elbow grease.
To wade by way of the choices, I talked to Anthony Zamora of C Rock Finishing in Oakland, California—right here’s what I discovered.

How simple is it to alter the colour of stained concrete flooring?
Not very. “Concrete is sort of a massive rock sponge,” Zamora says. “Earlier than it has something on it, it desires to absorb all the things.” That means that no matter has already been utilized to your concrete flooring has basically modified the fabric and can have an effect on coloration going ahead. It is a generalization, in fact—however when flooring are “stained,” or extra precisely, handled with a penetrating sealant, the colour has been absorbed to an unknown depth.
To alter the colour, we’re masking the 2 most typical options right here: You’ll be able to re-stain the flooring (by making use of a brand new penetrating sealant) or paint them (by making use of an industrial coating). Different choices embrace staining after which sharpening your flooring (which achieves a unique impact than simply re-staining) or masking them solely with a brand new materials, like a microtopping or concrete overlay.

How can I re-stain my concrete flooring?
To begin, you’ll must have the present floor mechanically floor down, each to prime the concrete to simply accept a brand new stain and to take away as a lot of the offending colour as doable. “You’ll be able to’t management how a lot stain permeated the concrete within the authentic course of,” Zamora says.It may very well be superficial and are available off pretty rapidly, or it might have permeated as deeply as half an inch down, which suggests it’s not going wherever. You’ll must mechanically grind your flooring to find out the next step.

What does it imply to mechanically grind the concrete?
You must use one thing more durable than concrete so as to grind it down, explains Zamora, which often means a substrate like steel, ceramic, or resin that’s been impregnated with diamonds. “Diamonds are so sturdy that they will really lower up the floor of the concrete.”