With the exception of side paddle machines, which are often used in addition to finishing for the piece dyeing of knitwear, most wet finishing machine used for wool knitwear, are based on a rotary drum, rather like a big version of a domestic rotary drum washing machine.

Although the basic action is essentially the same, rotary drum finishing machines can and do vary considerably in their severity of mechanical action and the degree of control by automation. I.e. Some machines have an in-built computer whereby all parameters such as speed, time, temperature and chemical additions can be set and controlled etc, whilst others in the main rely on the skill of the operator.

In addition some of the more modern machines are combined washers and extractors; this saves the garment having to be unloaded, and loaded into a separator hydro-extractor prior to tumble drying.

In practice wool knitwear can be wet finishing in each type of machine, but it must be remembered that firstly in comparison to knitwear made from Cotton and man-made fibres etc, that wool and knitwear made from can be regarded as being delicate, and can more easily suffer from mechanical damage (Holes, seam slippage etc) during the wet finishing operation. Secondly with the exception of say machine washable or Easy Care wool, wool has a unique and natural tendency for felting to occur, which can result upon over finishing.

Because of this, when wool knitwear is being wet finished it essential to set up the machine in terms of its mechanical severity so that it exerts a relatively gentle washing action. In addition greater care needs to be applied in the control of other finishing parameters, such as temperature, cycle time etc.

In addition to the actual wet finishing machine, the temperature, load, cycle time of the tumble dryer should be carefully controlled.