Accent Base Breathable Masonry Water Repellent Color Coating

PROSOCO BMC II Accent Base – Breathable Masonry Water Repellent Color Coating

PROSOCO Breathable Masonry Coating II (BMC II) Accent Base is a water repellent color coating engineered specifically for masonry substrates. It combines the aesthetic performance of high-quality paint with the protective function of a breathable water repellent, allowing water vapor to escape from within masonry while blocking destructive liquid water intrusion. Designed for contractors working on both historic and contemporary masonry structures, BMC II is suitable for interior and exterior applications across a wide range of masonry surfaces. This is a special order product — production lead times may apply.

Unlike conventional paints, BMC II uses a unique silicone emulsion formulation that delivers superior resistance to weathering, UV degradation, moisture, and soiling, making it significantly more durable and longer-lasting on masonry than standard coating products. Its highly vapor permeable film preserves the masonry's appearance and prolongs service life — a critical advantage over non-breathable coatings that can trap moisture and accelerate substrate deterioration. BMC II has field-proven performance on the U.S. Capitol and numerous historic and contemporary buildings across the United States and Europe.

Technical Specifications

Key Features & Benefits

Highly Vapor Permeable Formula

BMC II allows water vapor to escape from within masonry while simultaneously blocking liquid water entry. This breathability is essential for contractors working on masonry structures where trapped moisture can cause spalling, efflorescence, and long-term structural damage — helping protect the substrate and avoid costly callbacks.

Silicone Emulsion Formulation for Superior Durability

The unique silicone emulsion base makes BMC II more resistant to UV degradation, moisture, and soiling than most conventional paints. Contractors can expect exceptional color retention and longer service intervals between recoat cycles, reducing lifecycle maintenance costs for building owners.

Meets and Exceeds ASTM E 2357

BMC II is tested to and surpasses the requirements of ASTM E 2357, the standard for water resistance of exterior insulation and finish system assemblies. This gives contractors and specifiers confidence in the product's verified performance for water management on masonry facades.

No Primer Needed

BMC II is formulated for direct application to properly prepared masonry without a primer coat, reducing labor steps and material costs on the job site. A primer coat using PROSOCO Siloxane WB (diluted 1:19 with water) can optionally be applied if desired, with BMC II applied within 48 hours.

Easy Application — Roller, Brush, or Spray

Compatible with standard roller, brush, or airless sprayer application, BMC II fits into existing crew workflows without specialized equipment. The flexibility in application method lets contractors adapt to site conditions and project requirements.

Full VOC Compliance

BMC II is compliant with all national, state, and district AIM VOC regulations, with a maximum VOC content of 100 g/L. Contractors working across multiple jurisdictions or on projects with strict environmental compliance requirements can use BMC II without concern for regulatory conflicts.

No Harsh Odors — Interior and Exterior Rated

BMC II is suitable for both interior and exterior masonry applications and produces no harsh odors, making it practical for occupied or partially occupied structures. This expands the range of projects where BMC II can be applied without disrupting building occupants.

Common Applications

Historic Masonry Restoration

BMC II has a documented track record on landmark structures including the U.S. Capitol, making it a proven choice for restoration contractors working on historic masonry facades where breathability and color accuracy are critical.

Architectural Concrete Block (CMU)

Suitable for burnished, smooth, split-faced, and ribbed CMU block, with coverage of 100–150 sq. ft. per gallon. Commonly specified for commercial and institutional CMU construction to provide a finished, protected surface.

Concrete — Precast Panels, Cast-in-Place, Pavers

Applies to concrete brick, tile, precast panels, pavers, and cast-in-place concrete at 100–300 sq. ft. per gallon, providing water repellency and color uniformity across poured and precast concrete assemblies.

Fired Clay Brick, Tile, and Terra Cotta

Designed for use on fired clay brick, tile, unglazed terra cotta, and pavers at 150–350 sq. ft. per gallon coverage rates, protecting porous clay-based substrates against water intrusion while preserving their aesthetic.

Contemporary Commercial and Institutional Facades

Applicable to a broad range of exterior masonry substrates on new construction, providing lasting color and water protection without sacrificing vapor permeability on above-grade wall assemblies.

Interior Masonry Walls

With no harsh odors and a flat decorative finish, BMC II is appropriate for interior masonry surfaces in commercial, institutional, or industrial environments requiring a cleanable, water-resistant coating.

Compatible Materials

• Architectural Concrete Block (CMU) — burnished, smooth, split-faced, ribbed
• Concrete brick, tile, and precast panels
• Cast-in-place concrete
• Concrete pavers
• Fired clay brick
• Fired clay tile
• Terra cotta (unglazed)
• Clay pavers
• Marble, travertine, and limestone (consult datasheet for coverage)

Limitations

• Not for use on horizontal surfaces subject to vehicular or pedestrian traffic.
• Not suitable for application on some resin paints.
• Manufacturer does not endorse use of organic colorants; use of organic colorants for color matching may result in color fading.
• Do not apply if temperatures are colder than 40°F (4°C), or expected to be within 24 hours of application.
• Do not apply to surfaces hotter than 95°F (35°C).

Product Documents

• Product Data Sheet
• Safety Data Sheet (SDS)
• Safety Data Sheet – Spanish
• SDS – Canadian French
• VOC Compliance Documentation
• Product Test Data
• LEED Verification Letter
• SCS Certification

Application Instructions

Surface Preparation

1. Protect people, vehicles, property, metal, and all surfaces not set for coating from product, residue, splash, fumes, and wind drift using drop cloths or other proven protective material.
2. Protect and/or divert foot and vehicle traffic from the work area.
3. Surfaces must be clean, dry, and absorbent before application.
4. Correct the causes of moisture-related stains before application. Thoroughly clean efflorescence, algae, and other moisture-related stains.
5. In coastal areas, check for salt contamination prior to application.
6. Roughen or abrade glazed or glossy surfaces to ensure proper adhesion.

Priming (Optional)

1. BMC II requires no primer, but a priming coat may be applied if desired.
2. Use PROSOCO Siloxane WB diluted at a ratio of one part product to 19 parts water.
3. Apply BMC II within 48 hours of primer application.

Temperature Requirements

1. Do not apply if air or surface temperatures are below 40°F (4°C), or if temperatures are expected to fall below 40°F within 24 hours of application.
2. Do not apply to surfaces hotter than 95°F (35°C).

Application

1. Apply with roller, brush, or airless sprayer.
2. Refer to coverage rates by substrate type: CMU 100–150 sq. ft./gal.; concrete 100–300 sq. ft./gal.; fired clay brick/tile/terra cotta 150–350 sq. ft./gal.
3. Always test on a representative section of the actual substrate before full application.

Storage & Handling

1. Keep from freezing. Store in a cool, dry place at temperatures between 45–100°F (7–38°C).
2. Always seal container after dispensing.
3. Do not alter or mix with other chemicals.
4. Store containers upright and do not double stack pallets.
5. Shelf life is 1 year in tightly sealed, unopened containers stored per above conditions.
6. Dispose of unused product and container in accordance with local, state, and federal regulations.

Safety Data Summary

Hazard Information

• Flash point greater than 200°F (93°C) — low flammability risk under normal conditions.
• Freeze point 32°F (0°C) — protect from freezing during storage and transport.
• pH 9.0–10.0 — mildly alkaline; avoid contact with eyes and skin.
• 24-Hour Emergency Information: INFOTRAC at 800-535-5053.

Personal Protective Equipment

• Use appropriate safety equipment during application and handling as specified on the full product label and Safety Data Sheet.
• Review the full SDS prior to use for site-specific PPE requirements.

Safe Handling

• Always read the full label and SDS for precautionary instructions before use.
• Use appropriate job-site controls during application and handling.
• Do not alter or mix with other chemicals.
• Dispose of unused product and container in accordance with local, state, and federal regulations.

Frequently Asked Questions

Q: Does BMC II Accent Base require a primer before application?
A: No primer is needed. BMC II is formulated for direct application to properly prepared masonry. However, an optional primer coat using PROSOCO Siloxane WB (diluted 1 part product to 19 parts water) may be applied, with BMC II applied within 48 hours of priming.

Q: Can BMC II be tinted to a custom color?
A: Yes. BMC II is compatible with the CCE ColorCast Ecotoner colorant system for predictable color matching. BMC bases can be custom tinted by local distributors. Note that the manufacturer does not endorse the use of organic colorants, as these may result in color fading.

Q: Is BMC II suitable for both interior and exterior use?
A: Yes. BMC II is rated for both interior and exterior masonry applications and produces no harsh odors, making it practical for use in occupied or partially occupied structures.

Q: What temperature conditions are required for application?
A: Do not apply if air or surface temperatures are below 40°F (4°C), or expected to fall below 40°F within 24 hours of application. Do not apply to surfaces hotter than 95°F (35°C).

Q: Is BMC II VOC compliant in all states?
A: BMC II is compliant with all national, state, and district AIM VOC regulations and has a maximum VOC content of 100 g/L. See the VOC Compliance document linked above for jurisdiction-specific confirmation.

Q: Is BMC II a special order item?
A: Yes. BMC II is a special order product and production lead times may apply. Contact PROSOCO Customer Care at 800-255-4255 for your local distributor or for additional information.