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HessLite MAC Scratch & Brown Plasters are designed for plaster stucco applications where a lightweight rendering is desired or as a funtional bonding substrate (as part of the HessLite Installation System). Three product variations are available in the HessLite MAC Scratch & Brown plaster class.

HessLite^TM MAC^TM Scratch & Brown

Property Specifications: ASTM C926 | C1063

HessLite MAC Scratch & Brown is a premium, fiber reinforced, lightweight cement plaster designed for strength, efflorescence control and water resistance. HessLite MAC Scratch & Brown plasters provide low shrinkage, excellent workability, strength, and product consistency. Lightweight properties significantly improve freeze-thaw resistance, handling, and application.

HessLite^TM MAC^TM Scratch & Brown IWR

Property Specifications: ASTM C926 | C1063

HessLite MAC Scratch & Brown IWR is a premium lightweight fiber-reinforced scratch and brown with additional integral water repellent and efflorescence reducing additives.

HessLite^TM MAC^TM Scratch & Brown Poly

Property Specifications: ASTM C926 | C1063

HessLite MAC Scratch & Brown Poly is polymer modified premium lightweight fiber-reinforced scratch and brown with with additional polymer for increased flexural strength and water repellents for added durability and freeze-thaw protection.

USES: Use HessLite MAC Scratch & Brown plasters as the first coat (scratch) and the second coat (brown) for all types of Portland Cement lath and plaster applications. Use on interior and exterior base coats for stucco decorative wall systems. May be used on shower walls and Portland cement mortar beds for veneer and tile applications.

HessLite MAC Scratch & Brown plasters provide a better base for VBM Bonding Mortars than typical plastic cement job site mixes and are the recommended base mortars in the HessLite Installation System.

DATA SHEET: HessLite MAC Scratch & Brown • (PDF)

GENERAL DESCRIPTIVE and INSTRUCTIONAL INFORMATION

Description

Advantages. HessLite MAC Scratch & Brown Plasters have the following advantages:
• Lightweight for easy handling and reduced structural loading.
• Reduced efflorescence and water repellency.
• High compressive strengths.
• Fiber-reinforced and crack resistant.
• Low shrinkage.
• Water Repellent.

Colors. HessLite MAC Scratch & Brown plasters may be ordered in standard grey color and special order colors. The efflorescence control and water repellent properties help the long term appearance of colored plaster. For color consistency use the same water and finishing techniques. Color can vary dramatically. Test installation techniques prior to application.

Packaging. HessLite MAC Scratch & Brown plasters are available in 50 lb. moisture resistant bags.

Coverage. One 50 lb. bag will yield is approximately 0.62 cu.ft. per 50 lb. bag (approximately 20 sq.ft. at 3/8" thickness). Coverage will vary due to installation technique and coat depth.

Shelf Life. When stored in a cool dry area, with low humidity, shelf life is approximately six months to one year.

Efflorescence. HessLite MAC Scratch & Brown plasters have proven experience reducing efflorescence, however, due to variables beyond our control, we cannot guarantee efflorescence will not occur.

Suitable Substrates. See INSTALLATION; Substrates.

Limitations. Please note and abide by the following limitations:
• Do not apply when temperatures are below 40° F prior to cure.
• Do not add any admixtures without prior consent.
• Substrate must be sound—any cracks or excessive movement may telegraph through plaster or cause bond failure.
• Follow ASTM and ANSI guidelines for installation in high heat, cold or wind.
• Color may change due to differing water content, weather, absorption, and tooling techniques.
• Do Not Over Mix (3-5 min), as high air content will lower durability and bonding strength.
• Applicable building codes must be followed.
• Proper design and application procedures must be followed.

Technical Data

HessLite MAC Scratch & Brown plasters conform to IBC, CBC and ASTM C926 – Standard Specification for Application of Portland Cement Based Plaster. Compressive strength specimen must be air cured per ANSI 118.1 due to the high water retention and water repellency. Water content of approximately 30%. Product is composed of Portland Cement (ASTM C-150), Hydrated Lime (ASTM C-207), R-Mortar Aid, and graded lightweight aggregate.

Installation

Substrates. All substrates must be clean and free from any dirt, oil, paint, bond breakers or any substances which may hinder bond. All waterproofing and lath must be installed according to applicable building codes. The substrate must be structurally sound and conform to good engineering practices—meeting building code requirements. Movement in the substrate can cause cracking in the finished plaster and bond failure. All expansion or movement joints shall be brought through the plaster to the surface.

Mix Instructions. Proper mixing is critical for performance and workability of plaster.

1 • Start with six (6) quarts of clean water (water amount is approximately 28–30% of dry mix), add entire bag of HessLite MAC Scratch & Brown and mix at LOW SPEED for 3 – 5 minutes. DO NOT OVER MIX! Mixing should be done carefully to minimize air entrainment, as high air content will reduce performance.

2 • Allow to slake for 7 to 10 minutes. (Lightweight aggregate will continue to absorb water.) Gently re-mix and adjust consistency with additional water if necessary.

Application. Follow IBC, CBC, ASTM and local building codes for installation and curing requirements.

1 • Dampen absorptive substrate just before the application scratch coat. Dampen scratch coat before application of brown coat.

2 • HessLite MAC Scratch & Brown mortars are suitable for hand application or may be sprayed or pumped (test with spray equipment prior to using).

3 • Scratch/scarify/key the scratch coat before applying brown coat.

4 • Allow plaster rendering to cure according to stucco color coat, paint or bonding mortar requirements. Wet curing the finished plaster may be required in high heat or windy conditions.

NOTE: It is the responsibility of the user to insure the plaster is suitable for the intended application, that the substrate is properly prepared, and the application is performed correctly.

Admixtures. Replacing all or part of the mix water with R-FlexAd™ will increase flexural bond and impact resistance. Recommended for difficult substrates.

Warranty

The technical information and usage statements are based on our best knowledge. The contents of this specification sheet are presented for informational purposes only and do not constitute responsibility for their use. The manufacturer will replace only that material which is proven defective due to quality of the components or the manufacturing process.

Cautions

Prolonged exposure to dust may cause delayed lung disease. Eliminate exposure to dust. Use NIOSH approved mask for silica dust. Freshly mixed materials may cause skin irritation. Avoid direct contact where possible and wash exposed skin areas promptly. If any cementitious materials get into the eyes, rinse immediately and repeatedly with water and get prompt medical attention.

Note: Testing for crystalline silica (airborne particles of respirable size) has shown no measurable rates of Crystalline Silica (Si02) to be present in HessLite Scratch & Brown plasters.

Warning: Products containing crystalline silica (airborne particles of respirable size) are known to the State of California to cause cancer. For more information go to www.p65Warnings.ca.gov

DATA SHEET: HessLite Safety Data Sheet (SDS) • (PDF)