Foster® Monolar® II Mastic 60-38

1 of 92 products in this brand
Foster® Monolar® II Mastic 60-38 is a resilient elastomeric finish made from chlorosulfonated polyethylene rubber. This mastic is designed to protect thermal insulation and serve as a vapor-retardant finish for fittings. Its outstanding attributes make it well-suited for outdoor applications, offering superior color retention, chemical resistance, and durability.

Product Type: Coating

Features: Chemical Resistant, Color Retention, Fire-Resistant, Flexible, Good Toughness, Good Weather Stability, Outdoor Durability

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Identification & Functionality

Features & Benefits

Ready-to-Use Product Features
Product Highlights
  • FOSTER® MONOLAR® II MASTIC based on chlorosulfonated polyethylene rubber (formerly known as Hypalon®*) is a tough, flexible, fire-resistive, elastomeric finish for protection of thermal insulation.
  • It is also used as a vapor retarder finish for fittings.
  • It is excellent for outdoor use where good color retention, chemical resistance and durability are required.
  • MONOLAR® II MASTIC provides outstanding weather barrier and vapor retarder protection for most board stock thermal insulations except polystyrene.
  • It normally bonds well to aluminum foil facings, but a test application is recommended to confirm adhesion.

Applications & Uses

Limitations
  • Apply between 40°F and 100°F.
  • For best results, select Elastolar® 95-44 or Flextra® 95- 50 for insulation joint sealing under Monolar® II Mastic.
  • Always test plastic materials for compatibility when using a solvent-based product.
  • Outdoor horizontal surfaces must always drain completely.
  • A pitch of at least 1/2 inch per foot is required.
  • Make certain this product is completely dry and the area free from solvent odor if food is involved.
  • Select Monolar® Coating 60-95 (white) or 60-96 (gray) for airless spray or brush application.
Preparation and Application Information

Material Preparation 

  • Stir well.
  • Do Not Think.
  • Apply only to clean, dry surfaces.
  • Keep container closed when not in use to prevent solvent evaporation.

Application 

  • To prevent water vapor and moisture infiltration, proper and complete flashing is required.
  • Follow flashing specifications. 
  • Normal Service: Apply a tack coat of Monolar® II Mastic at a thickness of 1/32 inch (0.8 mm). This is equivalent to 2 gal./100 sq. ft. (0.8 l/m2). Embed Foster® MAST-A-FAB® or CHIL-GLAS® #10 White Membrane into wet tack coat. Smooth membrane to avoid wrinkles and overlap all seams at least 2 inches (5 cm). Apply a finish coat of Monolar® II Mastic at a minimum thickness of 1/16 inch. This is equivalent to 4 gal./100 sq. ft. This finish coat shall be applied no later than 2 hours after the tack coat and shall completely cover membrane. This application shall provide a minimum dry film thickness of 30 mils.
  • Severe and Cryogenic Service: After the first two coats have dried, apply an additional coat of Monolar® II Mastic at a thickness of 3/64 inch. This is equivalent to 3 gal./100 sq. ft. This additional application shall provide a minimum dry film thickness of 44 mils. On rough or porous insulation surfaces additional product will be required to achieve the full surface dry film thickness. The application rate may need to be increased by up to 20% or more to achieve minimum film thicknesses.
  • Trowel: Use clean tools. Work in long, even strokes to ensure uniform thickness. Wet tools with detergent foam (not soap) occasionally to prevent a buildup of dried mastic.
  • Rubber Glove: Best appearance may be achieved by smoothing wet Monolar® II Mastic with detergent foam (not soap) on clean glove or brush, being careful not to pick up any Monolar® II Mastic onto the glove or brush.

Clean Up

  • Use xylol (flammable) or chlorinated solvent (non-flammable) for cleaning equipment. Dried Monolar® II Mastic is extremely difficult to remove.

Properties

Physical Form
Typical Properties
ValueUnitsTest Method / Conditions
Average Weight / U.S. Gallon8.8 - 9.3lbs.ASTM D1475
Average Non-Volatile (by Volume)30.0% ASTM D2369
Average Non-Volatile (by Weight)43.0% ASTM D2369
Coverage Range6.0gal./100 sq. ft-
Coverage Range (Cryogenic Applications)9.0gal./100 sq. ft-
Drying Time (Set to Touch)3.0Hours-
Drying Time (Dry Through)48.0Hours-
Flash Point104°F
Water Vapor Permeance (at 54 mils dry)¹0.02permsASTM E96, Procedure A
Application Properties
ValueUnitsTest Method / Conditions
Service Temperature Limits (at coated surface)-40 to 250°F
Flame Characteristics
ValueUnitsTest Method / Conditions
Flame Spread ²20ASTM E84
Smoke Developed ²10 - 40ASTM E84
Note

¹ - Tested with reinforcing mesh. Monolar® II Mastic meets the permeance requirements of ASTM C755-19 for below ambient vapor retarder coatings.

² - Tested at coverage rate of 25 sq. ft./gal. Applied to 1/4 inch inorganic reinforced cement board. The flame spread may vary at different product thicknesses and/or when applied over other surfaces.

Regulatory & Compliance

Storage & Handling

Shelf Life
6 months
Storage Condition

Store between 40°F and 100°F.