• Description for Sika Flex-221

    A high-quality, multi purpose, non-sag, polyurethane sealant that cures on exposure to atmospheric humidity to form a durable elastomer. Bonds well to a wide variety of substrates

    *See Terms of Use Below

    Chemical Resistance Caustic solutions, Chemical Resistance: Diluted acids, Chemical Resistance: Fluid Resistance: Resistant to Fresh water, Vegetable and animal fats and oils, Chemical Resistance: Fluid Resistance: Resistant to Limewater, Mineral oils, Chemical Resistance: Fluid Resistance: Resistant to Sea water, Fuels, Sewage effluent
    Application Type Bond, Seal
    1 Part or 2 Part 1-Part
    Material Form Paste
    Substrate Ceramic, Metal primers, Plastics, Wood, Metals
    Industry Agriculture Machinery, Transportation Exterior
    Manufacturer Sika
    Chemistry 1-C polyurethane
    Cure Method Humidity
    Application Temperature (°F) 41 to 104
    Viscosity (cPs) Non-sag
    Color Black, Brown, Gray, Colonial white, Gray: Aluminum gray, White
    Aging Resistance Ageing
    High Temperature Resistance (°C) 140, 120, 90
    Low Temperature Resistance (°C) -40
    Durability Durable elastomer
    Density (g/cm³) 10.6 (lb/gal)
    Key Specifications ANSI (American National Standards Institute): ANSI/UL 723, For US: Meets approvals ASTM C920 types, International Organization for Standardization, TT (U.S. Federal Specification): Federal Specifications TT-S-00230C
  • Technical Data for Sika Flex-221

    • Chemical Resistance
      • Chemical Resistance : Fluid Resistance : Water Resistance - Resistant to Fresh water, Resistant to Limewater, Resistant to Sea water
      • Chemical Resistance - Caustic solutions, Fuels, Mineral oils, Sewage effluent, Vegetable and animal fats and oils
      • Chemical Resistance : Acid Resistance - Diluted acids
    • Application Type
    • 1 Part or 2 Part
      • 1-Part
    • Material Form
      • Paste
    • Substrate
    • Industry
      • Agriculture Machinery
      • Transportation Exterior
    • Chemistry
    • Cure Method
      • Moisture / Condensation Cure - Humidity
    • Color
      • Black
      • Brown
      • Gray
      • Gray : Aluminum - Aluminum gray
      • White - Colonial white
    • Key Specifications
      • ASTM (American Standard Test Method) - For US: Meets approvals ASTM C920 types
      • International Organization for Standardization
      • ANSI (American National Standards Institute) : ANSI/UL 723
      • TT (U.S. Federal Specification) : S-00230C - Federal Specifications TT-S-00230C
    Cure Specs
    Application Temperature (°F) 41 to 104
    Viscosity (cPs) Non-sag
    Linear Shrinkage (%) 5.00 Test Method
    Bond Strength
    General Bond Strength (psi) High
    Tear Strength (piw) Tear propagation resistance
    Tensile Strength (psi) 260 Test Method
    Material Resistance
    Non-Corrosive Non-Corrosive
    Aging Resistance Ageing
    Environmental Resistance Environmental resistance
    High Temperature Resistance (°C) 140, 120, 90
    Low Temperature Resistance (°C) -40
    Durability Durable elastomer
    Shore A Hardness 40 Test Method
    Elongation (%) 500 Test Method
    Flexibility Elastic
    Other Properties
    Glass Transition Temp (Tg) (°C) -45 Test Method
    Density (g/cm³) 10.6 (lb/gal)
    Business Information
    Shelf Life Details 12 months Cartridges and Unipacs, (CQP 016-1), 6 months Drums and Pails, (CQP 016-1)
    Shelf Life Temperature (°F) <77, <77
    Shelf Life (mon) 12, 6
  • Best Practices for Sika Flex-221

    *See Terms of Use Below

    1. Surface Preparation

      Surfaces must be clean, dry and free from all traces of grease, oil and dust. The substrates must be prepared in accordance with the instructions given in the current Sika Primer Chart. Advice on specific applications is available from the Technical Service Department of Sika Industry.

    2. Application

      Cartridges: Pierce cartridge membrane.

      Unipacs: Place unipac in the application gun and snip off the closure clip. Cut off the tip of the nozzle to suit joint width and apply the sealant into the joint with a suitable hand operated or compressed air gun, taking care to avoid air entrapment. Once opened, packs should be used up within a relatively short time. Do not apply at temperatures below 40°F (5°C) or above 105°F (40°C). The optimum temperature for substrate and sealant is between 60°F (15°C) and 77°F (25°C). For advice on selecting and setting up a suitable pump system, as well as on the techniques of pump operated application.

    3. Curing

      Sikaflex®-221 cures by reaction with atmospheric moisture. At low temperatures the water content of the air is generally lower and the curing reaction proceeds somewhat slower

    4. Clean-Up

      Use personal protective equipment (chemical resistant gloves/ goggles/clothing). Without direct contact, remove spilled or excess product and placed in suitable sealed container. Dispose of excess product and container in accordance with applicable environmental regulations.

    5. Removal

      Uncured Sikaflex®-221 can be removed from tools and equipment with Sika® Remover-208 or another suitable solvent. Strictly follow solvent manufacturer's warnings and instruction for use. Once cured, the material can only be removed mechanically. Hands and exposed skin should be washed immediately using a suitable industrial hand cleaner and water. Do not use solvents on skin!

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    *See Terms of Use Below

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Cure Time Test Methods
Cure Time Test Method
Linear Shrinkage Test Methods
Linear Shrinkage Test Method
5.00 % CQP 014-1, approx.
Tack Free Time Test Methods
Tack Free Time Tack Free Temperature Test Method
Work / Pot Time Test Methods
Work / Pot Time Test Method Temperature
Tensile Strength Test Methods
Tensile Strength Test Method
260 psi ISO 37, approx.
Elongation Test Methods
Elongation Test Method
500 % ISO 37, at Break
Shore A Hardness Test Methods
Shore A Hardness Shore Hardness Test Method
40 CQP 023-1 / ISO 868, approx.
Glass Transition Temp (Tg) Test Methods
Glass Transition Temp (Tg) Glass Transition Temperature (Tg) Test Method
-45°C ISO 4663, approx.