Millennium Water Block Mastic BP-300

Millennium Water Block Mastic BP-300 is a gray, high-performance, low-VOC, non-curing, gun-grade mastic engineered for unexposed waterproofing applications. This permanently flexible sealant provides a positive seal across multiple substrates, remaining watertight under harsh conditions. It is ideal for use around terminations, under flashings, and other protected roofing details.

Key Features

• Non-curing and non-skinning formulation
• Low VOC formula (<150 g/L), suitable for regulated markets
• Excellent adhesion to clean, dry substrates with no primer required
• Flexible and watertight, even under immersion conditions
• Permanently flexible and durable at low temperatures

Model: BP-300

Color: Gray

Cartridge size: 10.3 fl oz (305 mL)

Packaging: 30 cartridges per case

Coverage: 10–12 linear feet (3.0–3.7 m) per cartridge at ½″ bead

Shelf life: 24 months when stored unopened between 40 °F–110 °F (4 °C–43 °C)

Substrate adhesion: Concrete, masonry, gypsum, metal, glass, plastic, wood surfaces

Limitations:

• Not for exposed applications
• Not to be painted
• Not for use in direct UV light
• Not for contact with insulating glass sealants
• Not recommended in talc, oil, ice, snow, or wet conditions

• Clean all surfaces of dirt, dust, debris, oil, and contaminants.
• Ensure surfaces are sound, dry, and stable before application.
• If necessary, clean with approved surface cleaner before use.
• Cut cartridge tip and load into standard caulking gun.
• Apply a continuous ½″ bead of Millennium Water Block Mastic to the surface.
• Press materials firmly together to ensure full contact.
• Tool bead if required for smooth finish.
• Do not expose bead to UV or painted surfaces; use only in protected areas.

Q: What is Millennium Water Block Mastic BP-300 used for?
A: It is designed for unexposed waterproofing applications such as flashing terminations, under roof drains, metal counterflashing, and base seals.

Q: What is the coverage per cartridge?
A: Approximately 10–12 linear feet at a ½″ bead.

Q: Can BP-300 be painted?
A: No, it should not be painted or exposed to UV light.

Q: What is the shelf life?
A: 24 months in unopened cartridges stored between 40 °F and 110 °F.

Q: Is primer required before application?
A: No, it adheres well to clean, dry substrates without primer.