Setting the Dye in an Old Sweater?

I received an old sweater that was my grandfather's. It was originally white and his mother dyed it red, I'm sure with some kind of cheap home-dyeing kit, maybe Rit. I washed the sweater because it was dusty and it's bled and bled red dye everywhere. I've read about soaking in salt; does that actually work? Any other tips for setting the dye? I'm willing to do some experimenting. The sweater isn't particularly beautiful or complicated work, so it's more of a sentiment thing. Any help is appreciated!

By CG