Take a large bowl, and pour in a gallon of water. Then, using careful measurements, add one teaspoon of household general purpose ammonia to this. Mix it into the water, and then add in 1/4 cup of a protein-based laundry detergent. Most gel ink pen manufacturers, including Uni-ball, recommend ERA laundry detergent.
Next, take an old toothbrush, and swirl this around in the bowl for a bit, to make sure the detergent is thoroughly mixed into the water and ammonia. Then, dip the toothbrush into the mixture, and start scrubbing the gel ink stain with it.
Continue to scrub until you notice that you are beginning to break through the stain. A good idea would be to scrub in a circular motion, going clockwise at first, and then alternating and going counter-clockwise. Once the stain breaks apart completely, rinse the fabric using warm water, and then wash it as per the fabric directions.
Another method for removing gel ink stains from fabric involves the use of alcohol and vinegar. Take a medium sized bowl, and mix in 1 cup of rubbing alcohol and 1 cup of white vinegar. Then, proceed to dip a clean white cloth into this mixture, and generously dab the gel in stain with it, moistening it all the way through.
Allow the mixture to remain on the fabric for around 5 minutes – then, sprinkle some table salt onto the stain, and let this stay on for another 5 minutes. Once this time period has elapsed, use a toothbrush to scrape the salt off.
Then, start blotting the stain with a clean white cloth dipped in hot water – continue to do so until you notice the stain breaking apart and beginning to lift. If the stain doesn’t remove easily, you can add a drop of laundry detergent to it. Once the stain has been removed completely, use plain water and a clean damp cloth to rinse it one last time. After both the ink and the soap have been rinsed off, you can allow the fabric to air dry.