Butyl

Flexible liners have made a huge difference to pond construction. One of the first flexible liners and still the best is butyl rubber, which is used for a wide range of applications, from car windscreen sealant to tyres, each made to a different formulation, principally using petroleum products. Butyl for pond liners is rather like the inner tubes of bicycle tyres in appearance and characteristics, and while it is extremely flexible and stretches without breaking, it is very vulnerable to piercing with sharp objects.

Butyl therefore needs to be protected from objects such as flints, sharp stones or gardener's forks. It can however, be repaired if puntured by cleaning carefully and fitting with a butyl rubber patch. Although it has a very long life, it can be damaged if exposed to ultraviolet light and should be protected at all times, especially during construction.