Staining and sealing concrete -- it's easy!

A while back, in another feature on concrete, pavers, and stone, I touched on staining and sealing concrete. I recently had another great opportunity to stain and seal a 1300 square foot floor and, because of the advances in technology, it was a lot easier than last time. (If you need to repair the concrete first, take a look at Diane Rixon's great article here.)

Take a peek at the gallery; it will give you a sense of just how easy the process is, and we'll continue.

Staining and sealing concrete -- it's easy!(click thumbnails to view gallery)

First off, safety: the cleaning/etching material is a mild acid. It's formulated to take the top "skin" off a concrete surface so it will surely do that to you, as I discovered when I slopped some on my leg. No major harm, but I knew immediately what happened. The major problem, I'm guessing, is if you got some of this stuff in your eyes -- that clearly should be avoided. So ... eye, hand, and foot protection are all recommended, along with long pants and long sleeved shirts (neither of which I wore, naturally). Also, as you might imagine, a smooth, wet floor might readily lend itself to slips and falls. 'Nuff said.

Tools: We had all of these on hand. If you had to purchase them, it likely would run a couple hundred dollars.

• Broom for cleanup and spreading the etching liquid; no metal parts, please, or you'll see them go up in fumes.
• Vacuum to get all the dirt from the corners and under the door thresholds.
• A 5 gallon bucket to mix the acid with the dilution water.
• A hose and nozzle for wash-down.
• A mop (optional) for getting the acid into the corners -- wasn't a problem for me.
• A scraper (optional) for use if you have concrete lumps on the floor -- we did; it was very helpful.
• Painter's tape and masking paper to protect the baseboard and lower portions of the walls.
• A floor squeegee for easy removal of the surface liquid.
• A paint tray and a 1/2" nap roller with a long handle to apply the sealer.
• A sprayer, to apply the stain.

Time: It took two of us about four hours, in total, from cleaning to finishing the first coat of sealer.

Materials:

• One gallon of the diluted solution (one gallon acid to one gallon water) will clean and etch about 350 square feet of concrete. If your concrete is very smooth, and ours was, you use the stuff straight up (undiluted) to cover about 175 square feet. One gallon of acid costs about $22; we bought 7 gallons of Behr concrete cleaner/etcher for about $162 (taxed.)
• We used Behr semi-transparent stain at $23 per gallon; seven gallons cost us about $169.
• We used Behr sealer at the rate of about 150-300 square feet per gallon; because we had a surface that was reasonably smooth, we were at the high end of the application rate. We bought 5 gallons at $25 a gallon for a total of $131.
• For the bathroom floors, we used Behr non-skid floor finish additive; a $5 bag is mixed with each gallon.

The process: Our surface was smooth interior concrete but I have seen this process applied successfully to exterior concrete, pavers, and stone; if you do that, take care to protect your adjacent plants and other sensitive items. Although I have no personal experience with it, this procedure may also be used on vertical surfaces. Depending on the manufacturer, the process may vary, so pay attention. Remember, when all else fails, read the instructions.

1. As with just about all else in life, preparation is everything, so thoroughly clean the target surface; failure to do so will leave little-bitty (or maybe great big) lumps in the final product. A problem for us was bugs landing in the stain and sealer, and we surely didn't want Jurassic critters under the seal coat. You just have to be observant and pick the little rascals out as you see them.
2. Tape the paper to the baseboards, lower portions of the walls, and the doors. If you're concerned about splashing acid or stain on something, paper that area over.
3. If you have smooth concrete, as we did, use the cleaner/etcher at full strength; anything rougher (your determination) and the diluted stuff is good.
4. You can apply the acid out of a plastic bucket (as we did) or sprinkling can, but a sprayer is not recommended.
5. Spread the acid with a broom, covering all the surface, to include the corners and adjacent to the baseboards and door thresholds. Let it sit a few minutes, then scrub the area vigorously with your broom. A problem we had was that the humidity was so very low that the acid would tend to dry too quickly and that's a big no-no. Fortunately, with two guys working, we could keep the process going, but you'll have to really keep moving.
6. Without letting the acid solution dry on the floor, wash the floor thoroughly with fresh water, scrubbing the surface as you do so. If you have the ability to pressure wash the area, you're golden. We then used a floor squeegee to get rid of the surface water.
7. After the surface is dry, it should have the roughness of medium grit sandpaper; you may have to repeat the process if it doesn't.
8. Let the floor dry thoroughly before you apply the stain. We used the time to re-tape the protective paper on the lower walls.
9. Now we applied the stain with the sprayer, spraying in a circular motion, for a "mottled" appearance. (If you want a more uniform look, you'll have to roll the stain after application.) We applied the stain at a rate of about 300 square feet a gallon. Let the stain dry for four hours and then make a decision on a second coat, which we decided to apply. We let that coat dry overnight.
10. OK, getting close to the finish line. Apply the sealer with the roller and pan; it may go down "milky", but will dry clear. Let it dry a minimum of four hours, then apply an additional coat. After it dries, you may apply up to four additional layers.(Keep in mind that, at some future point, you're going to have to apply more sealer for protection of the stain.) We used a non-skid additive, in the sealer, for the bathrooms.
11. Most sealers will be dry to the touch in about an hour; check the manufacturers directions as to how soon you can walk on it, move furniture, or drive on it.

You can see that the process, while some time consuming, is pretty easy. You can do the job for a bunch less than you'd pay someone else. Why not give that old garage floor or back yard patio a new look? You know it would be really, really nice. Good luck.

Want more info.? Check out this video on sealing outdoor concrete.

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