Question: I am looking for a good adhesive for bonding glass to metal. The application is for a lighting fixture trim; it will be subjected to heat (approximately 100°C) and UV light. We currently use a moisture-cured silicone adhesive. Is there a better alternative (with a shorter curing time, improved performance, etc.)?

Answer: Bonding glass to metals can be done successfully, although it is often necessary to choose systems that have appropriate “adhesion promoters” to mitigate bond failure caused by hydrolysis of the adhesive-to-glass interface. Organosilanes are the preferred materials for this. Silicones are usually good adhesives for this type of application, but depending on a moisture cure can sometimes cause a few problems, particularly in the winter when humidity levels can be low.

You have several alternatives. First, you could use a two-component silicone that can give you very fast cure times. The negative side to this, of course, is that you will need to invest in and use a two-component syringe/cartridge system or meter/mix equipment. On the other hand, the increase in productivity often outweighs the investment required.

A high-performance, UV-cured acrylic might also be a good alternative; acrylics will cure in seconds and are usually very resistant to UV light exposure after curing without discoloring. You might also look at fast-curing epoxies, although some yellowing of the adhesive may occur under UV light. Another possibility could be a fast-curing, two-component acrylic system. This should give you a high-performance system that will be resistant to both heat and UV. 

 Any views or opinions expressed in this column are those of the author and do not represent those of ASI, its staff, Editorial Advisory Board or BNP Media.