TL-0007 — Chemical Compatibility Between VYCOR® Self-Adhered Flashings and Sealants Technical Letter
This technical letter is intended to provide information on chemical compatibility between VYCOR® Self-Adhered Flashings (including VYCOR® Plus, VYCOR® V40, and VYCOR® PRO) and various groups of sealants, used in the installation of exterior windows and doors.
GCP Applied Technologies, Inc. has performed comprehensive testing to determine chemical compatibility of various groups of sealants and VYCOR® flashings. Below are some general guidelines to assist in the selection of sealants used in conjunction with VYCOR® flashings. GCP strongly recommends that, in addition to the guidelines below, a small field “patch test” be performed on the VYCOR® flashing film and self-adhesive layer to determine compatibility and adhesion, since sealant manufacturer’s formulations vary.
Always follow sealant manufacturer’s recommendations for compatibility, application and use of their products.
Most sealants are compatible with VYCOR® flashings provided that the sealant is applied to the film component of the VYCOR® flashing. Some sealants, typically those with a high solvent content, may not be compatible with the self-adhesive component of the VYCOR® flashing. Therefore, any sealants with high solvent content are not recommended for use with VYCOR® flashings.
Both acetoxy and neutral cure silicones are compatible with Vycor® film and the self-adhesive layer. Most silicone sealants have good adhesion to the VYCOR® film but VYCOR® flashings may have only moderate adhesion to silicone sealants.
Moisture cure urethane sealants are compatible with the VYCOR® film and generally have excellent adhesion to it. They are also compatible with the self-adhesive layer provided the polyurethane sealant does not have high levels of solvent. VYCOR® flashings generally have excellent adhesion to these sealants.
Acrylic based sealants are compatible with VYCOR® film and the adhesive layer. VYCOR® flashings typically have moderate adhesion to these sealants. Acrylic Latex sealants, however, are generally slow to cure and may have poor adhesion to the VYCOR® flashing film.
Solvent-Based Polymeric Sealants
Solvent-based polymeric sealants are compatible with the VYCOR® film, but will only be compatible with the adhesive layer if the sealant is fully cured. Some of these sealants may contain high levels of solvent and can be incompatible with the VYCOR® adhesive. This group of sealants and VYCOR® flashings typically have excellent adhesion to one another. For other categories of sealants, refer to sealant manufacturer information for specific recommendations.