Dri-Fit is a polyester knit fabric developed by Nike to wick moisture away from your skin to the surface, where it evaporates. Sportswear made with this fabric keeps the wearer dry and comfortable during exercise. When a Dri-Fit shirt snags, your first instinct may be to cut the loose yarn loop off -- but this is by far the worst thing to do. As soon as the thread is cut and the fabric is stretched, the cut yarn will unravel and retract, creating a hole. Instead, use an iron to help get rid of the snag.
Lay your shirt flat on a table with the snag facing upward.
Place your hands face down with open palms on either side of the snag, horizontally.
Pressing down slightly, pull the fabric apart, away from the snag, moving your hands up and down on the table slightly.
Move your palms on either side of the snag vertically.
Repeat Step 3. The loose thread should recede into the fabric. If it does not, repeat steps 2 through 5 until it does, pulling harder each time.
Set the iron on a low setting appropriate for polyester. Hold the iron 1/2 inch from the snag and press the steam button for 10 seconds.
Press the iron on the snagged area three times, for two seconds at a time, to seal.
If the snag still doesn't come out, poke it gently through the fabric with the point of a knitting needle or similar pointy tool. Be careful not to create a hole.
Do not let the iron touch the fabric or you may burn it.