Teak is a beautiful wood that has a very high oil content. This oil protects the wood, making teak a very popular wood for outdoor or marine environments. While the oil protects the wood, it has a side effect of making gluing teak more difficult. By preparing the joint and using the right type of glue, you can glue teak using the same techniques as other woods. Once glued, the joint will be very strong and, in most cases, waterproof.
Work with a fresh teak cut, if possible. Glue the teak as soon as possible after the cut.
Wipe the surface to be glued with a solvent like turpentine. Teak is an oily wood and the oils can interfere with glue bonds.
Apply a wood epoxy to both sides of the joint. Marine epoxies work well and have the added benefit of being durable and waterproof.
Press the wood together and clamp it tightly for the time recommended by the epoxy manufacturer.
Carefully wipe any excess epoxy that is squeezed from the joint. Once epoxy hardens, it can be very difficult to remove. Use a solvent if necessary.
Gorilla glue is reported to work well with teak but is more expensive than marine epoxy.