The bladder is probably the most vital component in determining how a rugby ball performs. Bladders are available in different varieties and sizes, depending on the use of the ball. Traditionally, match and training balls use a natural latex bladder, which has high resilience, and provides a ball with good rebound characteristics. The down side of a natural latex bladder is that the surface is permeable, and allows air to pass through it, meaning that the balls need to be correctly re-inflated about once a week. There are advanced co-polymer bladders available, pioneered largely by Gilbert, which have equivalent resilience characteristics to natural latex, but that are non-permeable to air, therefore remaining inflated for much longer periods sometimes upwards of 1-2 months.
Natural Latex: Soft, bounces well, but leaks air (slowly).
Butyl Bladders: Offer an excellent combo of feel and air retention, typically in mid- to upper ranged balls*
Proprietary synthetics: Gilbert’s Air-Loc bladder is an excellent example of a co-polymer bladder that retains the qualities of natural latex without losing air. More expensive material used in higher quality balls but results in a ball that should hold air up to 1-2 months.