The outer edge-seal material in a dual-seal insulating glass unit, used to provide durability, adhesion, mechanical restraint, and, in structural glazing, a specifically designed structural function.
GlassRenu · Educational illustration
Meaning and boundaries
Not every secondary sealant is structural silicone or suitable for ultraviolet exposure, load transfer, or every spacer and glazing material.
Why it matters in glass restoration
Unknown secondary-seal type or condition makes perimeter treatment, solvent use, heat, and structural assumptions unsafe.
Related terms
References
- National Glass Association — GANA Glazing Manual, 2022 edition
Publisher’s original source - ASTM International — C1249 — Standard Guide for Secondary Seal for Sealed IGUs in Structural Sealant Glazing
Publisher’s original source - ASTM International — C1369 — Secondary Edge Sealants for Structurally Glazed IGUs
Publisher’s original source - National Glass Association and FGIA — Compatibility Testing of IG PIB Primary Sealant with Respect to Glazing Materials
Publisher’s original source