Acrylic sweaters do not shrink. In fact, acrylic fiber is more prone to stretching than shrinking. Washing instructions must be followed to ensure that an acrylic garment does not lose form and become baggy.
Acrylic fibers are similar to wool but do not absorb water readily. Acrylic also dries rapidly. If an acrylic sweater is washed in warm water in a washing machine and dried on low heat, it maintains form and does not shrink at all.
An acrylic sweater should never be washed in hot water the garment may lose form. It should be dried on a flat surface and ironed at low temperatures.