Spaghetti sauce on a white shirt has the potential to be a laundering disaster if it is not treated correctly and quickly. The sauce is made with oil, which helps the stain to set itself into the fibers of the shirt. This means you need to use the right cleaning solutions to get the stain out. You are more likely to succeed in completely removing the stain if you treat it right away.
Turn the shirt inside out. Turn the cool water faucet on over the sink and flush the spaghetti sauce stain.
Pour a capful of liquid laundry detergent onto the stain and gently pat it into the stain. Allow the detergent to work its way into the stain for several minutes.
Rinse the shirt well, removing all traces of detergent and as much of the stain as you can. Do not rub the shirt.
Pat vinegar into the stain with an old cloth, keeping the vinegar off the unstained areas of the shirt. Rinse the shirt one more time. Continue pretreating the stain with laundry detergent, rinsing it and treating the stain with vinegar until you have removed as much of the stain as you can.
Pretreat the stain with a prewash stain remover and wash the shirt.
Treat the stain with laundry detergent if the stain is still visible. Soak the shirt in warm water for 30 minutes. Wash with regular bleach if needed.