Ask Dr. Dave
Question: Can you advise on the best non-toxic, water-based adhesive for leather, rubber and fabric shoe soles, and folding of shoe uppers and linings?
Answer: Traditionally, solvent-based polychloroprene adhesives were used for this application. However, due to legislation on solvent emissions, most manufacturers use water-based systems these days. Water-based polychloroprenes are not as forgiving as their solvent-based counterparts, and you may find it necessary to use a two-component version to maximize performance. Aqueous polyurethane dispersions are another system that you should consider. They are usually applied to the substrates, dried and then heat-activated. Several types of these adhesives are available with different performance characteristics in terms of cure speed, flexibility, etc.
Question: I am looking for a good adhesive for bonding glass to metal. The application is for trim on a lighting fixture. It will be subjected to heat (~100°C) and UV. I currently use a silicone adhesive, but can you recommend anything with a faster curing time?
Answer: You probably have several alternatives. First of all, you could use a two-component silicone that can give you very fast cure times. The drawback to this, of course, is that you will need to invest in and use a two-component syringe/cartridge system or meter/mix equipment. However, the increase in productivity often outweighs the investment required. You might also look at fast-curing epoxies, although some yellowing of the adhesive may occur under UV light. A third alternative is to look at using a fast-curing, two-component acrylic system. This should give you a high-performance system that will be resistant to both the heat and the UV.