Before you wash your numnah in the washing machine, always check the care label for washing instructions. As a rule, numnahs should be washed at 30 degrees Celsius, preferably on a gentle cycle, although there are also manufacturers who specify higher temperatures.
You should not use fabric softener, as your horse may be allergic to the residues or find the smell unpleasant. A mild detergent or, in the case of white numnah, a special detergent for white laundry, is the best choice.
In a gentle wash cycle, the spin cycle is already reduced, otherwise a spin programme with low revolutions is recommended. You should also let your numnah air dry.