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If you catch a stain when it happens, you may be able to simply blot it out. This can help remove the stain before it becomes too much of a problem. While some ink will may stay in, blotting out the stain can help. Take a dry cloth and blot the stained area as best you can until it is dry. As you blot, move the cloth to a clean spot each time to avoid smearing the ink around. Before using any product on your clothes, you'll want to check the label inside your garment to make sure there aren't specific instructions for cleaning and to check the makeup of the fabric. Some fabric may contain polyester along with other types of fabric, so you'll want to make sure the different types of fabric can be treated in the same way as polyester if the makeup is mixed. You'll also want to make sure there aren't specific washing instructions. Some fabrics require hand washing while others require dry cleaning. Once you have blotted out the stain, choose a stain lifter. There are a variety of household products you can use to remove an ink stain from polyester.  Rubbing alcohol is a great stain lifter for polyester. Apply a small amount of rubbing alcohol directly on the ink spot. Then, gently blot with a clean cloth until the ink comes out.  Borax can also be used to remove ink from polyester. Add water to make a light paste and then apply it directly to the stain. Let it set for about 30 minutes.  Strong soap can also be used to remove ink stains. A laundry detergent or dish soap would work well. Pour it directly on the ink stain and rub the fabric together with your fingers. You may have to use a bit of force. After using the stain lifter of your choice, rinse the garment in cold water. If there is still a bit of ink left, rub the fabric together with your fingers while rinsing. This can help remove what's left of the stain.

Summary:
Blot the ink away. Check the care label. Choose a stain removal method. Rinse the stain under cold water.