Mercerisation of cellulosic fibres

A process for mercerising unconstrained cellulosic fibres comprises transporting the fibres along a transit path through a mercerising zone in which the fibres are contacted with a mercerising liquid, followed by a rinsing zone, in which the fibres are rinsed, wherein the unconstrained cellulosic fibres are held to prevent longitudinal shrinkage during transportation through both zones. The fibres, such as cotton fibres in sliver form, may be held by being pressed between a pair of belts through the zones. Apparatus for conducting the process contains a mercerising zone and a rinsing zone, and a conveyor comprising a pair of surfaces such as belt surfaces for holding the fibres to prevent shrinkage. The belts may be slightly elastic and under tension to slightly stretch the fibres. The belts wind around rollers separated a short distance apart to maintain tension on the belt and on the fibres therebetween.