DOWSIL™ 121 Structural Glazing Sealant

Structural Glazing & Bonding

A fast-curing structural silicone sealant for use in structural and weatherseal applications. With a fast cure and 1:1 mix ratio, DOWSIL™ 121 Structural Glazing Sealant answers the challenges facade contractors and manufacturers face with slow-curing, one-part sealants, mixing challenges of multipart sealants, and limited movement capability of tapes.

Product info


  • Approved for structural and weatherseal applications
  • Primerless adhesion to glass, alodine and anodized aluminum
  • Adhesion to DOWSIL™ brand structural sealants for reglazing applications
  • Adhesion and structural strength achieved in 24–48 hours
  • Meets ASTM C719 Class 25 (G, A, O)
  • Meets ASTM C1184 Structural Sealant Specification

Substrate Type

  • Alodine Aluminum
  • Aluminum
  • Anodized Aluminum
  • Glass



Dark Grey

Technical Information

Where to use Exterior
Paintable No
Time to cure 24 hours
Time to cure disclaimer DOWSIL™ 121 Structural Glazing Sealant cures in deep section within 24 hours and generally achieves full adhesion within 48 hours. However, full cure time depends on joint design, substrate type, temperature and humidity.
Container Type Cartridge
Shelf life 12 month
Sizes Sealant is available in kits of 400 ml net fill (2 x 200 mL)/13.5 fl. oz. net fill (2 x 6.8 fl. oz.) cartridges
Application method Pneumatic Dispensing Tool


Application Instructions

Contact our expert team for advice, training and application instructions for this product!