I’m a poor college student, so when I do my washes, I tend to mix colors and do it on cold. That way colors have less of a chance of running. It works better than you’d think. After a while my whites start to get a little darker, I suppose because of the blacks in the wash, including a shirt I just got (first wash!). This shirt, among a few others that could use some whitening, have that plastic shirt logo/band names/design.