Sealing Industrial Floors

RadonSeal Concrete Sealer

RadonSeal deep-penetrating concrete sealer penetrates up to 4” into concrete. It is waterborne (zero VOC’s), nontoxic, nonflammable, and non-hazardous. This reactive sealer reacts with lime and alkalis inside the concrete, expands and hardens as a silicate mineral. RadonSeal:

  • bonds,
  • strengthens,
  • preserves, and
  • seals concrete against liquids and gases.

The seal lasts for the life of the concrete. RadonSeal leaves no film or color on the surface, which remains paintable. When applied on bare (unpainted) structurally sound concrete, RadonSeal:

  • Stops water intrusion
  • Greatly reduces transmission of water vapor and gases
  • Hardens the surface against abrasion, wear, and dusting
  • Stops efflorescence
  • Protects against acids and most chemicals
  • Stops or reduces concrete pitting and spalling
  • Spills do not penetrate deep, easy to wash off
  • Encapsulates reinforcing steel against corrosion, reduces cracking
  • Purges dirt, minerals, hydrocarbon residues from the concrete
  • Prevents the growth of molds and algae
  • Primer - reduces the alkalinity of concrete, extending the life of paints or adhesives.

Selecting the Sealer

RadonSeal Standard is the best choice for poured concrete in good condition that is less than 15-20 years old.

RadonSeal Plus contains more minerals for sealing more porous concrete over 15-20 years old, or concrete that is already leaking, deteriorated or leached out.

Project Conditions

Damp concrete is acceptable, but not active water seepage, water-saturated concrete, or standing water.

Temperature of the concrete shall be above freezing during the application and for at least 72 hours afterwards. Ambient temperature shall be above freezing during RadonSeal application. Do not apply RadonSeal on hot concrete in direct sunlight and avoid windy conditions to minimize over-spray.

Newly poured concrete - let the concrete cure for at least 28 days.

Preparation and Surface Cleaning

The surfaces must be bare and sufficiently clean to allow RadonSeal to penetrate into the concrete.

Pressure-wash the surface (3,000 psi) to remove all dirt and residues. Squeegee or mop any water puddles or accumulated water.

Clean any oil slicks with proper solvents, laundry soap in hot water, or use Novion Universal Concrete Cleaner. Rinse off any residue.

Remove any paints, surface sealers, or mastics. Methods: shot blasting, sand- or water-blasting, floor grinders, a 36” disk sander with 16 grit sandpaper. Or use Novion Universal Concrete Cleaner for adhesives, tar, latex or acrylic paints, and pressure-wash off any residue.

Efflorescence (white mineral deposits) clogs up pores and would block the sealer. Extensive efflorescence is best removed by shot blasting. Or instead of hazardous inorganic acid etching, use RadonSeal Efflorescence Cleaner, which makes efflorescence disappear, and next day just sweep off the surface and apply RadonSeal.

Remove any molds, mildew, or algae. Mild cases may be cleaned with a solution of chlorine bleach or borate and a detergent (e.g. Dawn dishwashing liquid). A much safer solution indoors it to use our BioZap Mold and Mildew Remover. Or spray on our Efflorescence Cleaner to to remove both molds and efflorescence at once. When dealing with molds, wear goggles, gloves, and protective clothing. Extensive mold infestation requires a professional.

Hard-cap machine-trowelled finish, which is very smooth and almost shiny, impedes proper penetration of the sealer. RadonSeal takes over 10 minutes to penetrate into the surface. Shot blasting is the best method to open up the surface. Alternatively, use Ion-Bond Armor instead of RadonSeal.

Mask glass and aluminum as well as glazed ceramic tiles, copper, machinery, and fixtures or just wipe off any over-spray right after the application. Cover up any vegetation, plants and shrubs.

Testing Vapor Transmission

Testing will indicate how porous is the concrete and how to seal it best. Perform calcium chloride tests approximately every 1,000 sq. ft. The worst readings (lbs/1,000 sq. ft./24 hours) will determine the recommended treatment for the floor:

  • below 10 lbs … 2 spray-on applications of RadonSeal
  • 10-15 lbs. … 3 applications of RadonSeal
  • over 15 lbs. … 3 app’s of RadonSeal plus 2 app’s of Ion-Bond Armor

Newly poured concrete can be tested after 90 days.

Spray Equipment

RadonSeal is applied with a low-pressure sprayer. Use a spray nozzle with a fan pattern rather than conical. Available sprayers:

  • mobile pesticide sprayer powered by battery or a gasoline engine
  • professional airless paint sprayer with a lacquer tip set at 40-60 psi and a long hose (100-150 ft.) for mobility
  • hand-pump garden sprayers.

The Spray-On Application

Dampen the concrete first to reduce surface tension and help the sealer penetrate deeper. Spray with water or flood the surface, squeegee, and let partially dry. Or apply when still damp after pressure-washing.

Spray the sealer in a thin continuous film - do not over-apply, do not let the sealer puddle. Spread out any puddles with a broom.

Spray on RadonSeal in 2 or 3 successive applications about 15–30 minutes apart, while the concrete is still damp. Seal a section at a time.

Safety glasses and a breathing mask are recommended. If splashed in the eyes, wash out with clean water. If swallowed, do not induce vomiting, but drink water for dilution and consult a physician. Check the MSDS.

Coverage Rates

Coverage depends on the concrete’s porosity and composition. If the concrete is older or more porous, or high in alkalis, it will consume more sealer.

Spray on a thin film at a rate of 450–300 sq. ft./gal. for each application, i.e. total consumption 150–100 sq. ft./gal.


Wipe off unwanted over-spray while still soft (10–15 minutes). Clean spraying equipment with water.

The concrete will appear dry in 3–4 hours and is usable for foot traffic.

In about 6 (to 12) hours after RadonSeal application, flood the surface with water and remove any residue with a wet floor scrubber or a stiff deck brush. This helps the sealer set and ensures a paintable surface.

RadonSeal will purge minerals, efflorescence, and dirt from the concrete for several days. Sweep the floor with a floor scrubber, stiff brooms, or a pressure-washer.

Let the sealer cure for at least 4 days before covering the surface or exposing it to any spills.

Before painting the concrete, let it thoroughly dry out – 5 days for porous paints or 10 days for paints not permeable to moisture.

Delivery, Storage and Handling

RadonSeal is shipped in 5-gallon pails or 55-gallon drums.

It can be packaged in shipping pallets of 4 drums or 36 pails, or shipped as loose drums. The purchaser is responsible for off-loading. Polydrums require careful handling.

RadonSeal shall be stored in its original unopened containers in an area away from direct sun at 40º to 80º F temperature until ready for use. Protect from freezing during shipping or storage. The shelf life is 2 years.