670HS Karna-Sil Ultra (High Solids Low VOC Silicone Coating)

    670HS Karna-Sil Ultra (High Solids Low VOC Silicone Coating)

    Available in: 5 gallon pails & 50 gallon drums

    Karnak 670HS Karna-Sil Ultra is a white, single component, high solids, moisture curing silicone coating that produces a durable elastic coating with  exceptional weathering and water resistance characteristics.



    Cool Roof Rating Council (CRRC)
    1. Solar Reflectance: Initial 0.87 3 year 0.70
    2. Thermal Emittance: Initial 0.89 3 year 0.90
    3. SRI:
    Initial 110 3 year 86


    VOC: 306 g/L


    Coverage Calculator

    • 1.5-1.5 Gallons per 100sf**


    This is intended as a general guideline only, coverage can vary based on many factors.


    Newly Sprayed Poly-Urethane Foam or Previously Coated Silicone roofs
    (No Primer required): Apply 670HS Karna-Sil Ultra directly over newly sprayed polyurethane foam, or pressure-washed, clean and dry Silicone coated roofs.

    Metal, BUR (Built-Up), Modified Bitumen, Concrete, Masonry, TPO, PVC, Hypalon, and EPDM roofs (Requires Epoxy Primer): Pressure-wash roof, and let dry prior to primer application. Apply 180 Karna-Sil Epoxy Primer and allow to cure before applying 670HS Karna-Sil Ultra. 670HS may be used on vertical as well as horizontal applications. All surfaces must have positive drainage. Note: Vertical application may require multiple coats to achieve desired film thickness.

    Physical Properties

    Weight per Gallon: 10.7 lbs.
    Solids by Weight: 96% ASTM D-1644
    Solids by Volume: 96 % ASTM D-22697
    Color: White
    Reflectivity Initial: 0.87 ASTM C-1549
    Aged: 0.70 ASTM C-1549
    Emissivity Initial: 0.89 ASTM C-1371
    Aged: 0.90 ASTM C-1371
    Initial SRI: 110
    Aged SRI: 86
    Hardness Shore A: 50 ASTM D-2240
    Elongation: 192% at 73°F ASTM D-2370, 216% at 0°F ASTM D-2370
    Tensile Strength: 331 PSI at 73°F ASTM D-2370, 432 PSI at 0°F ASTM D-2370
    Application temperature: 40°F and rising
    Storage temperature: 50°F – 90°F. Dry environment
    Permeance: 5.9 perms ASTM E-96
    Service Temperature: -15°F to 180°F
    Cure Time: 2-8 hrs. (Temp. & Humidity Dependent)

    Preparation & Application

    Surfaces to be coated should be dry, clean, and free of dirt, dust, grease, oil and loose rust or coating. Power wash surfaces with 799 Wash-N-Prep Roof  Cleaner or 507 SPC Primer/Wash (EPDM Only) and water. Wash roof surfaces with a minimum of 2000 psi. taking all necessary precautions to avoid  damage to the roof system. Patch and repair all seams, flashings, damaged areas, leak and cracks with Karna-Flex WB, Karna-Flex, 550 Patch-N-Go self  sealing tape or appropriate sealants or caulking materials.

    Karnak 670HS Karna-Sil Ultra can be applied in a single coat application (Material warranty only), or a multi-coat application (Required for Labor & Material Warranties). Allow first coat to cure 2-8 hours before applying second coat (dependant upon temperature and humidity). Subsequent coats should be applied within 24 hours of prior applications to insure uniform adhesion. Applied coating film should be even and free of pinholes. Coverage will vary  depending on the surface to be coated. To improve aesthetics, impact resistance and toughness of the coating, ceramic roofing granules should be applied immediately into the top coat after application. Back-roll granules in, allow coating to cure then blow off or vacuum loose granules. Mix coating prior to  application with a 3” diameter mixer (5-gallon pail) or 6” diameter mixer (55 gallon drum). Once product is mixed, the entire container should be used.  670HS Karna-Sil Ultra may be applied by brush, roller or airless spray equipment. Apply at temperatures 50°F and rising. Do not apply if rain is expected  within 24 hours after application. Commencement of work by the contractor implies his approval of the roof surface.

    For spray application, a high-pressure airless spray unit with a minimum of 3500 psi working pressure at the gun tip should be used. The pump must have a  3 gallon per minute output. Hoses should be jacketed for prevention of moisture contamination. Hoses should have a ¾” ID and tip size should be a  minimum size 0.030 orifice. Do not use with hoses that have been used to spray acrylic coatings.

    Single Coat: Apply at 1.5 gallon per 100 square feet (25 dry mils)
    Multi-Coat: Apply each coat at 1.5 gallon per 100 square feet (25 dry mils x number of coats)

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