Hardtop glass butyl or urethane?

[Brave Salmon]

Glass company wants to use butyl in lieu of urethane to install my front and rear glass. Should I be concerned or is this a good way to go? Installer says he can get a better fit with less mess and no leaks.

[65 Cobra Dude]

In my experience, butyl works fine if the glass has a painted border because the paint hides the fiberglass edges. If there is no paint on the borders, urethane works better because it spreads thicker on compression and hides the fiberglass. The Gen III Coupé has no paint and I used the butyl and I am not happy with it. I’m going to strip it out and use the urethane once I paint the border.

Hope this makes sense?

Henry

[Arrowhead]

The only issue I have with urethane is it's too good. Once you set that glass your screwed if you ever have to remove it. It will be very difficult to remove the glass without damaging the thin fiberglass lip (ask me how I know).