How do you lock in fabric dye from running?

Here is a useful link (though slightly disappointing if you're looking for a simple solution). Apparently, the traditional salt/vinegar solutions don't really work depending on the dye. I personally would be a bit nervous taking a chance... but this site does give some products that hand-dyeing people use that are better:

http://www.pburch.net/dyeing/FAQ/settingdye.shtml