Some wool blankets can be washed in a washing machine, but only if allowed in the manufacturer's instructions or on the label. Manufacturers often coat wool blankets in a resin that protects the fibers from damage in a washing machine. Blankets without this protection must be dry cleaned in order to prevent shrinkage and other problems.
Wool blankets that can be washed in a washing machine will have the words "washable" or "washing machine safe" on the label. These should be laundered only in cold water and with a detergent that is safe for wool. Soak them for 15 minutes in the water and soap, then run them through a short gentle cycle followed by the rinse cycle.
One way to keep wool blankets clean without using the washing machine is to brush them on a regular basis. Spread them flat on a clean, hard surface, then brush the fibers in their natural direction with a soft-bristled brush. This removes dust, dirt and other contaminants without damaging the fibers.
Never put a wool blanket in the dryer, as this can shrink the fibers and leave the blanket feeling rough. Instead, hang it to dry outside or in the laundry room. Avoid direct sunlight for prolonged periods of time, as this can fade the colors in the wool.
For heavily-soiled wool blankets that cannot be laundered in the washing machine, a dry cleaning service is the best solution. Dry cleaning can often remove extremely tough stains, including blood and ink stains.