Official C.R. Laurence Product CRL Gunther Ultra/Bond Mirror Mastic is a high quality adhesive formulated to provide a strong, permanent bond between electro-copper-plated glass mirror and various substrates. It has been field and laboratory tested for compatibility with silver, copper and mirror paint backing. Gunther Ultra/Bond's viscosity provides for a build out of 3/4 inch (19 millimeters) and can be compressed to 1/32 inch (.8 millimeter) for mirror installations requiring close tolerances such as overlays, mirrored furniture and medicine cabinets. Gunther Ultra/Bond at 72 degrees Fahrenheit (22 degrees Celsius) achieves approximately 30 percent strength in 24 hours, full cure up to 605 psi in 28 days. Easy working consistency year round. Will adhere to a wide variety of substrates including drywall, wood, metal, glass, marble and tile. All porous substrates should always be sealed with an acrylic sealer like href="/apps/sitesearch/search.aspx?query=GN6">Gunther Prime-N-Seal Primer . Gunther Ultra/Bond should be applied in vertical beads the full length of the mirror, five to six inches (127 to 152 millimeters) apart. Allow three inches (76 millimeters) from the mirror edge to begin or end a bead. Note: Not for use on acrylic mirror, vinyl backed safety film, treated wood, plastics or styrofoam. Do not apply to wall paper or paint. Not designed to be exposed to continuous U.V. light. Mechanical support systems are recommended for all mirror applications. This includes the use of mechanical fasteners at the top of the mirror.