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    ​​​​​​​​​​​​​​WS Flash / Flashing Primer

    WS Flash ​​​​is a patented, 30-mil thick, self-sealing, self-healing composite membrane of polyester fabric and rubberized asphalt.

    WS Flash is compatible with Finestone Base Coats and Finestop RA/RS/VB.

    ​WS Flash is supplied in rolls, on release paper, for easy application.

    ​Self-sealing, self-healing
    ​Maintains a seal when penetrated by fasteners
    ​Finestop, Finestop RA, Finestop VB and Finestone Base Coats can be applied to polyester face
    ​Use as part of adhesively applied EIFS
    ​Supplied in rolls on release paper
    ​Easy application


    Used as an air/water-resistive barrier accessory to connect different air barrier materials or assemblies together to make the air/water-resistive barrier continuous.

    ​Flashing at sills, approved sheathing joints, rough openings, and terminations. As an expansion joint seal.

    Flashing Primer is to be used under WS Flash membrane on these acceptable substrates and other surfaces:

    • Wood framing (Note: Verify adhesion before applying to wood that has been treated in any way.)
    • ASTM C1177 sheathings; e.g. eXP™, GlasRoc®, Securock™ and DensGlass™.
    • Water-resistant core gypsum sheathing (ASTM C79/ASTM C1396)
    • Cement-board (ASTM C1325 Type A Exterior)
    • Masonry
    • Exposure 1 or exterior plywood sheathing
    • Exposure 1 OSB
    • Steel framing
    • WS Flash (itself)​​​
    • Finestone Air/Water-Resistive Barriers​


    WS FLASH 4: 10.2 cm x 30.5 m (4" x 100'), 9 rolls per carton

    WS FLASH 9: 22.9 cm x 30.5 m (9" x 100'), 4 rolls per carton


    WS FLASH 4: 274.3 Lin m (900 Lin ft) per carton

    WS FLASH 9: 121.9 Lin m (400 Lin ft) per carton

    WS Flash / Flashing Primer Product Bulletin

    WS Flash / Flashing Primer Product Bulletin


    Material Safety Data Sheets