Q: I replaced one-fourth of a concrete driveway when a new water line was installed. That section is white; the older sections are gray. It looks awful. If I paint the concrete, I can imagine chipping and wear will require almost annual re-painting. How about some sort of stain over the old and new concrete that will be permanent?
A: Your instincts are right on. Don’t paint the two-toned driveway under any circumstances. Stain it. All a coat of paint will get you is a film on the concrete that will eventually come off. As the moisture level of the concrete changes with the seasons the paint will loosen. Maintenance will be a nightmare and will become more difficult with each passing year.
Coloring the driveway with concrete stain is the way to go. These stains are either acid washes or water based. Both work by reacting with the chemicals in the concrete.
Stain is color particles suspended in a thin liquid. Stain soaks into the concrete and colors it without hiding its natural appearance or texture.
Stains work best on the rougher surfaces produced by a wood float or broom finish. They don’t work so well on slick troweled slabs. Because most driveway finishes are rougher, there are more nooks and crannies for the particles to penetrate, resulting in a more consistent color. Also, note that because concrete stain is a chemical reaction, surfaces previously treated with muriatic acid or otherwise acid-etched cannot be stained.
Concrete loses its water content and gains strength over time. This process is called curing. A new pour must cure for at least 28 days before staining, according to the Portland Cement Association.
This can be a do-it-yourself project, but if you choose to go it alone, we caution you to not try to do too much at one time. Concrete slabs have control joints, or cuts in the slab that tend to allow any cracking to form at the cut. Mask off each segment with tape and cardboard and do one segment at a time.
The job is a pretty straightforward six-step process:
1. Decide on the type of stain you want to use. Acid stains are harder to apply but produce better color patterns and penetrate the concrete surface. Water-based stains are easier to use but don’t have a deep, rich color.
2. Measure the length and width of the driveway to get a square-foot total of the area to be covered. Buy enough stain. Follow the manufacturer’s recommendation for coverage and add a fudge factor. You should be able to return unopened pre-mixed cans. Also keep in mind some stains may need several coats to get the result you want.
Be forewarned that at $100 and up a gallon, concrete stain isn’t cheap. Depending on the porosity of the slab, a gallon should cover from 150 to 250 square feet.
3. Clean the concrete thoroughly to prepare the surface for the stain. A pressure washer comes in handy here. Remove everything from the concrete. Use a concrete degreaser to remove stains and dirt. Allow it to dry completely and then sweep it off with a clean broom.
4. Suit up to protect your skin from the stain. Wear long pants, boots, a long-sleeve shirt, goggles, a hat and gloves.
5. Spray the stain on the concrete using a pump sprayer for a wider, smoother broadcast of the material. Start in a corner and work in 2-foot sections. Layering and drying times can be found in the manufacturer’s instructions for your specific type and brand of stain.
What you will see at first is not the end color. It takes up to eight hours for the chemical reaction to take place. No pets or people on the concrete stain during this time. If that happens, foot or paw prints may become a permanent part of your driveway.
6. If desired, seal the concrete with a sealer after the stain dries completely. A sealer helps protect the stain and can add a polished look to the concrete. Apply the sealer with a roller.
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