Supporting photo - Iso-Tek 8555

Formulated for Porous Block

A penetrating silane/siloxane water repellent designed for CMU and porous block. This formula impregnates cementitious substrates while reducing chloride and water absorption; eliminating efflorescence and scaling.

Reduces Water & Chloride Absorption

Longer service life and higher performance levels make it especially suited to prevent deterioration of concrete and porous mineral substrates.

The proprietary nanotechnology offers deeper penetration when compared to traditional silane/siloxane isomers resulting in an even longer service life.


  • Moisture Absorption
  • Chloride-Ion Ingress
  • Salts
  • Water Intrusion
  • Efflorescence
  • Leaching / Scaling / Staining


  • Porous Block / CMU Block / Split Face Block
  • Concrete / Brick / Masonry
  • Horizontal / Vertical Reinforced Concrete

Certifiable Greatness

The Clear Choice

Cinderblock, split-faced, and textured block are far more porous than cast-in-place concrete. Because of this, regular silane sealers penetrate too deep to provide adequate surface protection. Iso-Tek 8555 CMU blends the perfect amount of absorption and surface bonding to deliver the best in water repellency and protection.

WATER ABSORPTION (%) 0 5 10 15 20 25 30 0 HOURS .5 1 1.5 2 2.5 Untreated CMU55% Solvent-based Silane100% Pure SilaneIso-Tek™ 8555 CMU
Supporting photo - Iso-Tek 8555

Dries Clear

Provides a flat, natural finish and dries completely transparent with no visual change to the aesthetics. Once cured the concrete will return to its natural appearance.

Product Details

    • Composition - 55% actives nanotechnology driven high-performance actives with a unique oligomer for a greater build inside porous surfaces.
    • High resistance to wind-driven rain - Penetrates into the concrete chemically reacting within the pores and capillaries creating a long-lasting hydrophobic surface that beads water.
    • Excellent Resistance to Chloride-ion Ingress - Forms an effective chloride screen dramatically reducing chloride ion ingress preventing deicing salt / chloride damage.
    • Reduces Efflorescence - Reduces vapor and moisture to eliminate mineral movement transmission
    • 100% Breathable - Non-film forming. Allows moisture within the concrete to escape without adverse effects to the sealer. Does not trap moisture.
    • High Resistance to Alkali Attack - Protects concrete by limiting the long-term swelling reaction that occurs between cement paste and amorphous silica.
    • Longer Service Life - Higher actives formula
    • Department of Transportation - Meets or exceeds DOT specifications
    • Ultra Low VOC - Approved for use in all 50 states.
  • Surface Prep

    1. New (green) concrete must be properly cured. Concrete should obtain 80% of design strength, typically achieved within 14-28 days.
    2. The concrete or concrete block substrate must be structurally sound and clean of oil, grease, dirt, wax, curing compounds, efflorescence, paints, previous sealers, adhesives and other contaminants that might interfere with the penetration of the sealer. Power wash, acid etch or mechanically scarify as necessary to achieve the desired surface condition. Allow for proper dry time before application. May be applied to slightly damp surfaces, although maximum penetration is achieved on dry substrates. Do not apply if standing water is visible.
    3. Surface and air temperatures must be at least 20oF during application. Surface and air temperatures should not exceed 95oF. Do not apply when temperatures are expected to fall below 20oF within 8 hours or when rain is expected within 12 hours following application. Keep material from freezing. If freezing conditions exist before application, let the substrate thaw before application. Do not apply during inclement weather or when inclement weather is expected within 12 hours.
    4. Crack, patching and expansion joint sealants can be applied before or after application; always test for compatibility and adhesion.
    5. Protect people, property, vehicles, window glass, roofing materials, plastic products, shrubbery, landscaping and all surfaces not set for treatment from overspray.


    1. Always test a small area before application to ensure desired performance, aesthetics, coverage rates and to verify application technique. Let test area dry thoroughly, 5-7 days, before inspection.
    2. Stir material throughly before and during application. Do not dilute or alter material for purposes other than specified.
    3. Apply with a roller, brush or low-pressure non-atomizing sprayer. Apply to saturation and roll or broom out any puddles until the sealer penetrates the substrate. If it starts to rain, stop treatment and cover the impregnated areas.

    Dry Time

    Typical drying time is 4-6 hours at 70oF and 50% relative humidity. Cooler temperatures or higher relative humidity can extend the drying time. Treated surfaces will be ready for pedestrian and vehicle traffic within 24 hours. Water repellency will continue to develop within 7 days of application.

    Clean Up

    Clean equipment, tools and surfaces with mineral spirits. Unused or old material may be disposed of in a waste disposal site in accordance with local, state and federal laws.


    Avoid contact with skin, eyes and clothing, do not take internally. Use appropriate safety equipment during application and handling. Please refer to the safety data sheet (SDS) for additional precautionary instructions before use.

    Best Performance

    • Proper application is the responsibility of the user.
    • Will not inhibit water penetration through unsound or cracked surfaces with defective flashing, caulking or structural waterproofing.
    • Spills should not be allowed to sit for extended periods of time, clean all spills in a timely manner.
    • Iso-Tek 8555 CMU should not get into direct contact with bitumen.
    • Take caution with specially coated glass. Test small areas before application to ensure the product does not discolor the coating.
    • Plastic windows will turn opaque when sprayed with this product.
    • Not intended for below-grade waterproofing.
    • Will leave a residue on nonporous materials such as glass, metal and painted surfaces.
    • Make sure the most current versions of technical data sheets and safety data sheets are being used.


    1 coat: 200 - 600 square feet per gallon. 2 coats: 50 - 300 square feet per gallon. Variations in texture and porosity of substrate will affect the coverage and performance of the product.