How do I protect autographs on a t-shirt from fading?

Question:My 4 yr old daughter got her Kasey Kahne t-shirt signed by Kasey, with a black Sharpie brand marker, last night at a local dirt track, and being a 4 yr old, she got some of her drink on the shirt and it needs washed. As much as the autograph means to her, I want to protect it from fading in the wash, and her to still be able to wear the shirt as well. Is there a product out there that can be sprayed on the fabric to keep the ink from fading?

Answers:
AS WEIRD AS IT SOUNDS, SOAK IT IN VINEGAR. MY SON HAS A GLOBETROTTER JERSEY AND THE AUTOGRAPHS HAVE HELD FOR OVER THREE YEARS. WORKS WELL FOR TIE DYE OR ANY OTHER COLORED SHIRTS THAT COULD FADE. (AND OF COURSE WASH IT BEFORE SHE WEARS IT OR SHE'LL WALK AROUND SMELLING LIKE A DILL PICKLE. :)