MIRRORWELD ADHESIVE

It bonds the metal rearview mirror button to the inside of a windshield, either to install a new mirror or to reattach one that has fallen off. The package holds two parts: 0.4 mL of adhesive and 0.6 mL of accelerator. Use it on metal buttons only, not plastic buttons, and not on an exterior side mirror.

No. Both components are needed for the repair to hold. Wipe the accelerator onto the marked spot on the glass and onto the button, let it dry for about 30 seconds, then place a single drop of adhesive on the button and press it into position. Using the adhesive alone gives an unreliable bond that is likely to let go.

Hold the button firmly against the glass for two minutes, then wait at least one hour before you mount the mirror on it. Full strength comes at 24 hours, so avoid adjusting the mirror hard during the first day. Apply between 50 and 75 degrees F; a windshield that is cold or baking in direct sun is outside the working range.

Acetone is the thing to try, since it softens cured cyanoacrylate. Work slowly and keep it off the dashboard, trim and paint. The instructions say not to attempt removal once the button is installed, so treat this as salvage rather than a planned step. Next time, mark the button position on the outside of the glass before you commit.

200 degrees F is the maximum working temperature once cured. That is above anything the inside of a windshield normally reaches, including a car parked in summer sun. The cured bond also resists impact, moisture, humidity and vibration, which is what keeps a mirror button attached over road miles and through repeated door slams.

This is not what it is made for. MirrorWeld is formulated to bond a metal mirror button to windshield glass, and J-B Weld does not list bonding a mirror by its silvered backing as an intended use, so we cannot confirm it is safe for that coating. Use a mirror mastic that is specifically rated as safe for silvered backing.