Choosing a secondary sealant for insulating glass

Primary and secondary seals

Stage	Role
Primary seal (butyl)	Mainly limits moisture and gas passage.
Secondary seal	Completes the perimeter sealing system.

Compatibility between the secondary sealant and butyl is a key consideration. White mineral oil in a material may adversely affect the butyl seal, causing black staining or seal failure; visual appearance alone cannot establish compatibility.

This 2024 application guide refers to standards GB 24266-2009 and GB/T 29755. Material selection should also take account of the insulating glass’s structure and conditions of use, with compatibility among all components of the sealing system in mind.

Selection checklist

• The insulating-glass unit’s structure and intended use.
• Compatibility with the butyl seal and other components.
• Joint design and exposure conditions.