Repair of Cement Joints
Cracked or open cement joints, paricularly in exterior applications, can present a serious preservation problem because they permit water to penetrate the internal system of a pigmented structural glass veneer. Rusting metal anchors or deteriorating mastic adhesive may be the result.
Although the traditional joint cements are easily coored and may be neatly applied, they are no longer recommended for the repair of pigmented structural glass because their longevity is limited. Present-day silicone compounds, on the other hand, offer flexibility, relative impermeability to moisture, ease of installation, and a long lifespan. The proper color match can be obtained by mixing the compound with tinted polyester resins.
Patching Glass Cracks
Any glass panel that can be repaired should not be replaced. The decision to repair or replace damaged historic pigmented structural glass panels always needs to be made on a case-by-case basis. In many instances, the damage may be so minor or the likelihood of finding suitable replacement glass panels so small that repairing, reanchoring, and/or stabilizing the damaged glass is the only prudent choice.
A slightly chipped or cracked pigmented structural glass panel left unrepaired will inevitably become a source of water infiltration. Careful patching of those cracks with an appropriately colored, flexible caulk will deter moisture penetration while still allowing expansion and contraction with temperature fluctuations. Although patching is by no means a permanent solution, it will help to protect the material from further damage due to the effects of weather.