Surface Preparation Is Critical for Staining Concrete
LastiSeal® Concrete Stain & Sealer combines a deep-penetrating waterproofing sealer and concrete stains in one product. While the molecules of the polyester-based sealer will reliably penetrate even into tighter substrates, the color stain pigments have a much harder time.
The key to success is a proper surface preparation and suitable conditions:
- CLEAN – Free of any contaminants like oil, grease, efflorescence, paint, old sealers.
- POROUS – Smooth, hard-troweled surfaces require acid etching or grinding.
- DRY – The concrete must be thoroughly dry. Avoid applying outside if rain is expected within 24 hours.
- TEMPERATURE – Air and surface temperatures of 70 – 90 °F are optimal.
- ALKALINITY – Concrete must be well cured with low alkalinity or acid-washed to reduce pH below 9.
How to Test Concrete Porosity
The surface must be porous enough to allow the stain granules penetrate. As a good indication, you can perform the Eyedropper Test:
Get an eyedropper in a drugstore, fill it with water, add a drop of liquid soap (which breaks surface tension), and shake. Lay about a dozen drops on the concrete surface. If the drop just sits there for over 10 minutes or it spreads out leaving a large damp spot the size of a quarter, the surface is not porous enough. But if the size of the damp spot is a nickel or dime, it is “fine.” All areas will not absorb evenly but at least 70 percent of the drops should meet this test.
Test the Stain Color and Penetration First!
LastiSeal is guaranteed to waterproof concrete for at least 15 years. However, the color stain pigments are much more dependent on proper surface preparation and application by the user. Therefore, the penetration of the color stain itself is not guaranteed!
IF THE STAIN DOES NOT PENETRATE, THE PROBLEM IS THE CONCRETE PREP OR THE APPLICATION BY THE USER.
Purchase a sample of LastiSeal® Concrete Stain & Sealer first. Perform the following tests three days after the application:
Wet rag test: Rub the surface with a wet rag. The stain should not come off! If it does, the stain has not penetrated well enough and may wash off easily.
Fingernail test: Using a fingernail or similar, confirm that there is no color film to flake off.
The Surface Must Be Bare and Clean
Remove all contaminants like dirt, paints or sealers, curing or form release compounds, adhesives, efflorescence (“white powder”), oil, grease, mildew, rust, and similar. This may require power washing, acid etching, shot blasting, sandblasting, grinding, scarifying, or just washing and scrubbing with a deck brush.
Note: Contrary to a popular myth, acid etching will not remove most paints, sealers, and oils.
- If you remove the paint from the surface, the pores may be still filed and may prevent proper penetration of the stain. Solvents, thinners, and some strippers fill the
pores with the paint instead of lifting it. You may need our professional-strength Lightning Strip Paint & Mastic Remover.
- Previously applied concrete sealers which fill the pores in concrete will hinder proper penetration of LastiSeal Concrete Stain and cleaning the surface will not remove them. Contact the manufacturer. Remove curing agents on young concrete.
- Acid stained concrete:
- Remove the topical sealer fist.
- Deeply embedded oil may be a problem with garage floors even after cleaning or grinding the surface. Use our penetrating degreaser/cleaner Novion Universal Concrete Cleaner. Afterwards, remove any residue with a power washer or rinse it off with water and scrub with a stiff bristle brush.
- Use our RadonSeal Efflorescence Cleaner to avoid hazardous acids, acid-neutralization and rinsing steps. Then, just let the concrete dry out and sweep the surface before sealing with LastiSeal Stain.
For more information on cleaning and preparing concrete surfaces please check Frequently Asked Questions.
The Concrete Must Be Dry
The concrete must be thoroughly dry – a dry surface is not good enough. The concrete must be dry inside to allow LastiSeal Sealer penetrate 2 to 4 inches into the pores.
Let the concrete dry out for at least two days after a rain or at least three days after pressure washing, depending on temperatures, wind, and humidity. Avoid rain for at least a day after the outdoor application of LastiSeal.
Good ventilation, fans, or dehumidifiers will speed up drying.
Mask glass, metals, and surfaces that should not be stained. When sprayed on glass, wipe off with a wet rag before it dries or clean it later with Novion Universal Concrete Cleaner. LastiSeal does not harm vegetation.
Spray on LastiSeal® Stain in a continuous, thick, glistening film and back-roll any puddles with a roller. Spraying is preferable to rolling, particularly on outdoor concrete, because it will not leave overlapping roller marks caused by fast drying.
When spraying is not practical, you can use a roller. Make sure to deposit a thick enough glistening film like with a sprayer instead of just smudging it on the surface. Maintain a “wet edge” to avoid darker overlap areas. If you must stop during the application, end at a control joint or similar break.
- Application Tips:
- LastiSeal Stain may be applied with a brush or sponge to create design features but heavily enough to also waterproof the concrete.
- Staining walls is more difficult than floors because the sealer tends to run down. When sealing walls, spraying should be followed with a roller to pick up drips and to even out the color.
Considering applygin a stain to your cocnrete patio? Check out our step-by-step guide on How to Stain a Concrete Patio
Do Not Over-Apply!
All the stain must absorb into the surface without leaving a film. Too much stain makes it susceptible to hot tire pick-up or it may wash off after a heavy rain or snow melt. In contrast, well-applied LastiSeal Stain cannot be removed with a pressure washer. It is used in truck stops and even a bus depot in sunny Florida.
If uncertain about absorbency of the surface, use only one application as the safer approach. Before applying a second application, test on an inconspicuous spot first to make sure the stain is absorbing well enough.
Second application may be needed to waterproof a very porous substrate or to achieve a more intense color, particularly with lighter stains. For deep-seal waterproofing, it’s best to apply it about half an hour to an hour after the first application. However, light additional applications can be applied at any time in the future.
Customers feedback and tips on Staining Concrete with LastiSeal Concrete Stain & Sealer
Confirm that the Stain Has Penetrated
Perform the “wet rag” and “fingernail” tests (see above) on the stained surface.
What to Do if the Stain Has Not Penetrated?
Even when the color pigments have not absorbed well, the LastiSeal® Sealer has likely penetrated and permanently waterproofed the concrete.
You can wait for rain to gradually wash the unabsorbed stain off outdoor concrete but meanwhile, it will look unsightly. You can remove the stain with a high-pressure washer or by flooding the surface with water and scrubbing it with a stiff bristle brush. Or use our Novion Universal Cleaner. This will not affect the waterproofing sealer deep inside the concrete!
On indoor concrete, you can “lock in” the stain by coating it with a clear acrylic or urethane coating to protect it against water and wear.
None required. If you wish to clean the surface occasionally, we recommend a weak solution of Dawn dishwashing liquid in water.
Avoid deicers and rocks salts on outdoor surfaces. They are strong enough to “eat away” plain concrete and would gradually remove the LastiSeal color stain from the surface. Unfortunately, vehicle tires will carry road salt on to the driveway.
Snow shoveling and scraping can damage the concrete surface and scratch the LastiSeal stain. Use a shovel with rubber blade. LastiSeal will make snow and ice slide off.
Deep, visible scratches can be easily touched up with the LastiSeal® stain.
Refreshing the color: If the color fades or the surface gets worn say, after 5 or 7 years, wash it off with water and mild soap and let dry for couple days. Re-spray with a light application of LastiSeal Stain & Sealer to avoid building up the stain on the surface. It will not absorb very fast, because the pores are filled and sealed.