In the early 1930’s, oil-base glazing and caulking compounds were commonly used for sealing joints in building construction. There was little movement to contend with, but control of air and moisture was needed. With the architectural swing to curtains walls and larger lites of glass, industry quickly moved from putty and mastic glazing into high performance polymer sealants.
Today, a variety of preformed glazing tapes and rubber-set elastomeric sealants are available. These are formulated to be non-hardening, provide good cushion for the glass, and absorb thermal movement.
Wet / Dry
Extruded and gunnable sealants offer the advantage of proven adhesion to most glazing substrates, thereby assuring a positive seal against moisture infiltration. Dry systems, utilizing compression, offer effective installation cost savings. Combining these advantages into a single, workable system would, in effect, give the “best of both world“. Tremco pioneered this combination system approach with a 3-component design called the Tremco Glazing System.
• 1) 440 tape to the exterior
• 2) Heel bead gunnable acrylic sealant
• 3) Interior gasket-used primarly for appearance and shimming
This represent the first compatible wet/dry system from one manufacturer.
Tremco recently engineered a glazing system that offers the security of a wet sealant and shim, plus the easy installation of dry gasket glazing. The Gasket or WEJ and the shim in polyshim tape are made of identical compounds and of compatible durometer, such that a balanced compressive force exists on both sides of the glass. Called the POLY-WEJ system, it is ideal for applications such as well-designed curtain walls, flush windows, rain screen walls, and off-set vertical and horizontal strip windows- areas that used to present formidable glazing problems. The system is composed of:
• 1) Highly elastic POLYshim tape
• 2) Neoprene compression gasket
• 3) High performance sealant for toe heel or heal bead
“Dry glazing“ is the common designation for systems utilizing reformed rubber gaskets as the seal for glass and panels. Gasket usage is growing because they can be installed in-plant and transported in the sash to the project, therefore reducing on-site labor cost.
There are two main types on engineered gasket systems-compression and lock-strips. High performance, compression gasket glazing systems usually employ soft, closed-cell gaskets on one side of the cell glass and a firm, dense gasket on the opposite side. By careful sizing of the gaskets, the cellular member, being soft and spongy, will compress between 25-40%, and forma tight seal when the dense gasket is positioned between glass and glazing stop.