Turn your wool sweater inside out before washing.
Fill a large bucket with lukewarm water and add the recommended amount of mild wool laundry detergent. Mix the detergent into the lukewarm water to ensure it's fully dissolved.
Submerge your wool sweater in the wash water. Swish it around in the detergent water before allowing it to soak for up to five minutes.
Squeeze and gently lift the fabric to move the soapy water through the wool fibers. Dunk the wool sweater up and down in the water to gently agitate it.
Empty the bucket of the soapy water. Fill the bucket with cool water and add a quarter cup of white vinegar to help rinse the detergent out of the wool fibers while setting the colors. Carefully squeeze the rinse water through the sweater to push out the detergent. If needed, make a fresh batch of rinse water and rinse the wool sweater again until all detergent is removed.
Hold the sweater above the bucket and squeeze it to remove excess rinse water. Squeeze the sweater together without twisting or wringing it to avoid stretching the wool. Lay the sweater on a thick, absorbent towel. Roll the sweater inside the towel and press down to absorb more moisture from the sweater.
Position the wool sweater on a sweater drying rack that allows air circulation to move around the sweater. Gently shape the sweater to ensure it dries in the right shape. Allow the wool sweater to air dry completely.