Silicone sealants resist sunlight, ozone and temperature extremes better than organic sealants, and low-modulus grades handle movement of plus 100 and minus 50 percent. They are the only sealants used for structural glazing. Paint will not stick to cured silicone, some grades pick up dirt, and their fluids can stain porous stone. Once silicone has been on a surface, few other sealants will bond there.
Silicone on the glass and metal, but use the non-staining grade on the limestone or you'll get halos.
Old silicone residue on a joint face kills the adhesion of urethane and STPE sealants, so reseals over silicone get ground or abraded back to clean substrate.
Also heard as
- silicone sealant
Related terms
SSG
Structural silicone glazing, where glass is held to its frame by silicone instead of exterior caps or stops.
Bleed
Staining from fluids or plasticizers that migrate out of a sealant into porous stone or masonry.
Movement capability
How far a sealant can stretch and compress, as a percentage of joint width, while keeping its seal.
Modulus
How stiff a cured sealant is, meaning how much force it pulls on its bond faces when stretched.