Abstract: Apparatus for mercerization of cellulosic fabrics with liquid ammonia. Denim fabrics and the like, especially those made from open-end spun yarn, have liquid ammonia for mercerization applied thereto by a metering roller while tensioned. The metering roller has a number of deep engravings formed in the periphery thereof, which may be in the form of a truncated cone or a tetrahedron. Pile or ribbed fabrics are treated by application of liquid ammonia with a metering roller to the back of the fabric, while tension is maintained by relatively gentle apparatus, such as a pinned drive cylinder. When fabric direction is changed, soft rollers engage the fabric face to change the direction, and the fabric face is brushed with rotary driven brushes of Nomex or the like. Final ammonia removal from the fabric is facilitated by passing the fabric over a large cylinder with a perforated surface, steam transfer occurring across the fabric in the steam chamber.