Grab a paper towel, tissue or any disposible cloth immediately within reach. Dampen it with lukewarm water.
Blot the ink gently, making sure to use a clean section of the towel each time. Be careful not to touch any other part of the sweater with the ink-stained towel.
Dip a cotton swab into a bottle of isopropyl rubbing alcohol. Place the swab onto the stain and slowly rub the ink in one direction. Refrain from rubbing the stain in circles. Add more alcohol and change the cotton swab as needed. Other useful cleaning agents include hairspray, ammonia or nail polish remover.
Mix equal parts water and baking soda in a small bowl. Stir the solution together with a spoon. Pour the solution directly onto the stain and wait five minutes. Blot the stain using a paper towel or cloth.
Rinse a clean towel under warm water and wring out most of the water. Squeeze the rest over the stain. Wipe the baking soda solution clean.
Turn the knit sweater inside out. Set the washing machine to a cold, gentle wash. Add detergent to the water. Place the knit sweater in the machine. When the cycle is finished, slip your hand into the sweater and turn it right-side out.
Examine the ink stain spot. If there is any ink left over, spray a commercial ink stain remover directly onto the stain. Let it sit for a few minutes and follow the manufacturer's directions. You may need to immediately wash the sweater again. When the cycle is finished, lay the sweater on a flat, clean surface. Spread out the arms and smooth out the body. Allow it to dry over night.