Penetrating Concrete Sealers
Basement Waterproofing, Radon Mitigation

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Application Instructions & Tips
for LastiSeal Masonry Color Sealer

Storage

Keep unused sealer in a closed container in protected storage out of direct sunlight at 40–90°F. KEEP OUT OF THE REACH OF CHILDREN.

Avoid freezing, do not store outdoors in freezing weather.

Shelf life – 1 year.

Do not thin the sealer or dilute with water – it would negatively affect the resulting seal and color.

Color Sealer pail labels (in PDF):

Ambient Conditions for Application

The air and surface temperatures must be above 60 °F during the application. The surface temperature should remain above 50 °F for at least 24 hours. This presents no problem in basements during the winter – the ground temperature and heating keep the concrete surface warm enough. Tip: Store the sealer at room temperature before application.

On outdoor applications, avoid hot surfaces in direct sunlight. It would dry out the sealer before it can penetrate. In hot weather, apply in the morning while the surface is still cool or apply to areas in shade. Or apply in the afternoon after gets cooler but not too late, in order to avoid the chance of dew falling on the wet surface.

Avoid rain for at least 24 hours after the application.

Surface Preparation

The surface must be clean and dry. Remove all dirt, paint or sealers, adhesives, efflorescence ("white powder"), oil, grease, mildew, rust, and other contaminants. You can use our Lightning Strip Paint Remover, Novion Universal Concrete Cleaner, or Efflorescence Cleaner (check out Concrete Cleaners). Then, remove all residue with a pressure washer or wash and scrub with a deck brush.

New concrete – allow its pH value (alkalinity) to drop to below 10! (Most paints and floor coverings require a pH below 9.) "Green" concrete is too caustic (pH of 11-12) but its pH will usually drop to below 10 in 3 to 12 months. Thanks to acid rain, it drops faster in outdoor concrete. You can get pH test strips in drugstores and on the Web. To reduce the pH value of concrete, use a mild acidic solution (e.g. muriatic acid 1 : 10 solution, a low-pH cleaner, citric acid or vinegar solution) followed by thorough rinsing. Using the pH test kits, confirm that the average pH is below 10, preferably closer to 9, but not less than 5.

Very hard-troweled or polished concrete with a high sheen would prevent proper penetration of the stain. (No paint or stain would adhere either.) Open up the surface by vacuum shot-blasting, light sand-blasting, grinding or sanding. Or etch with muriatic acid, neutralize with a baking soda or ammonium solution, and thoroughly rinse off any residue. Typically, this is needed on floors in shopping malls or warehouses but not on most residential garage floors.

Mask glass, metals, and surfaces that should not be stained. The sealer does not etch glass but once dry, it has to be scraped off.

Test samples

We strongly recommend that you first test with a couple of samples to make sure it is the best color and translucence for your concrete, and to confirm that the color has penetrated into the surface. (Note that the Color Sealer is non-returnable.) If you have to, the stain can be scrubbed off with a stiff brush and water a day or two after the application.

Personal Protection

Masonry Color Sealer is water-based, non-toxic, nonflammable, non-carcinogenic, and non-hazardous. No hydrocarbon solvents and very low VOCs. None or a slight odor. Does not harm vegetation or grass.

Using splash goggles is a good industrial hygiene practice. Gloves will keep the sealer from drying on hands. No other special precautionary measures are normally required.

Good ventilation (ideally 10 air changes per hour) will remove the evaporating water.

Keep Stirring!

Very important – STIR WELL BEFORE AND DURING APPLICATION! The color pigment settles.

Stir particularly well off the bottom. Best to pour the sealer into another clean container, ensuring that no pigment is left at the bottom, and thoroughly stir.

Keep stirring while applying the sealer. If using a sprayer, keep shaking it.

Application Equipment

Color Sealer can be applied by spraying or rolling. Best to use both – spray it on in a continuous, thick, glistening film and then, back-roll any puddles to avoid leaving darker or shinier areas. However, some prefer the mottled look from puddles.

Use a low-pressure sprayer with a fan-tip nozzle – the common hand-pump garden sprayer or any low-pressure sprayer (20–30 psi pressure). A roller with about a 1/4" nap, preferably mohair.

Spraying is preferable to rolling because it tends to deposit more sealer on the surface for a better seal and deeper color. With rollers, novices just smudge the sealer on the surface and leave little pigment or sealer to penetrate into the concrete. Spraying is better for outdoor applications where wind or low humidity may dry out the sealer before it can penetrate.

Click to enlarge!

Application

During the application, maintain a “wet edge” to avoid darker overlap areas.

If you must stop during the application, end at a joint or some other architectural feature. If none is available, use blue painters’ tape to create a clean edge. When resuming application, re-mask with the tape on the already colored side. When sealing a floor, plan ahead to leave a way out without stepping on the wet surface.

Let dry out before applying the second application next day, at least after 12 hours.

Staining walls is definitely more difficult than staining floors because the sealer runs down, making the color uneven. Spraying should be followed with a roller but that is difficult on "bumpy" surfaces like stucco. Repeated applications make the color more even. Regardless of the color, the sealer still waterproofs the substrate.

Number of Applications

Two applications are standard and are required to waterproof concrete or masonry. Two applications also provide a more intense color.

If you prefer a lighter color, use only one application and to waterproof the concrete, apply as the second application LastiSeal Concrete & Brick Sealer in either Matte or Satin version. (Not in reverse – the color stain would not penetrate into already sealed surface.)

Good-quality poured concrete will normally not absorb a third application. But three applications may be needed when waterproofing very porous materials:

Older poured concrete over 30-50 years old
Standard concrete blocks
Cinder blocks
Splitface blocks
Pavers, colored pavers.

Abnormally porous pavers may require multiple applications, as well as when reducing concrete dusting on a very porous concrete.

There are materials with pores so large that they are almost impossible to waterproof – some lightweight CMUs, splitface blocks, or cinder blocks, and masonry that has already badly deteriorated due to extensive water seepage.

Coverage

Depends on the porosity of the surface.

Approximately 200 sq.ft./gallon (1,000 sq. ft. per pail) for the first application. Second applications next day at approx. 300–400 sq.ft./gallon.

When waterproofing standard poured concrete in 2 applications, we estimate 600–700 sq.ft. per 5-gallon pail (120–140 sq.ft. per gallon).

Combination with RadonSeal

For the tightest seal against water vapor and radon gas, seal the concrete first with RadonSeal Deep-Penetrating Concrete Sealer. Let cure for at least five days and sweep off any purged minerals. Then, apply one light application (at 300–400 sq.ft./gallon) of LastiSeal Color Sealer. Since the concrete is already deep-sealed, it will not absorb much of the color and the resulting color will be lighter, more translucent.

Cleanup

Wash all tools and equipment with soap and water as soon as possible. Any spills may be cleaned with soap and water before they dry. Flush all spray equipment with soapy solution.

Removing the stain or any over-spray: Scrub off using a stiff bristle brush and plenty of water. If already cured for several days, remove the stain with Novion Universal Concrete Cleaner.

Has the Sealer Penetrated?

The "wet rag test": Let cure for 3 or 4 days and then, try to scrub it off with a wet rag. The stain should not come off. If it does, the stain is not adhering well enough. It could wear off or wash off easily.

The "finger nail test": The color stain should be below or inside the surface. There should be no layer similar to a paint film sitting on the surface. Using a finger nail or similar, the color should not flake off.

How Come the Stain Has Not Penetrated?

Common pitfalls:

New concrete – too caustic with pH above 10. It has "burned off" the color.
Very hard, machine-troweled surface – the stain could not penetrate.
Hot surface or very windy, dry conditions – water has flashed off before the sealer could penetrate.
Wet concrete – the sealer could not penetrate into the pores.

Note that the sealer component may have penetrated and waterproofed the concrete even though the color stain pigments have stayed on the surface.

Curing and Maintenance

Ready for foot traffic in 2 to 5 hours. Allow at least 3 days before vehicular traffic and 5–7 days for heavy vehicles. The sealer fully cures in 1 to 2 weeks.

Because the sealer is largely below the surface, there is little impact on surface friction. Depending on the surface and the application, a smooth surface may slightly bead.

Most floor adhesives and water-based paints adhere very well to the Color Sealer. But do not use latex paints (they do not bond chemically) or solvent-based paints (could smudge the stain).

On outdoor surfaces, avoid deicers. They are strong enough to "eat away" plain concrete and can gradually remove some of the LastiSeal color from the concrete.

Maintenance – none required. If you wish to clean the surface occasionally, we recommend a weak solution of Dove soap. Deep, visible scratches can be easily touched up.

Refreshing the color: If the surface gets worn off after say 5 or 10 years, wash it off with water and soap and when completely dry, re-spray it lightly with the Color Sealer. It will not absorb fast, because the pores still remain filled and sealed.