I would wash them with detergent plus non-chlorine bleach (oxygen bleach) at the hottest temperature they could stand, for the longest available wash cycle (or soak them with occasional stirring, since oxygen bleach is slow-acting at less than hot temperatures). Note that items marked for "cold" wash can be washed at 85F. The "cold" setting on most washing machines is more like 60-65F. The "warm" setting on some machines is 85-90F, which means one could wash cold-wash items on the warm setting. Even if your "warm" setting is 100-105F, occasional washing at that temperature is unlikely to ruin the T-shirts, and will work better than a cooler temperature.

I don't think the dingy gray is from colors rubbing off, rather it's from cold washing. It might take more than one proper washing and bleaching to undo it.

Hmm, I've had much better luck with colors... I tend to choose wash temperature based on cleaning requirements, not the care label. So I wash bed linens and bath towels at 120F, dish towels at 158F. Some of these items are patterns, with colored and white areas. The colors don't run and they come out looking fine (other than puckered edges on the dish towels), even though they're labeled "warm" or maybe "cold". I've had just two color bleeding incidents: A blue bathmat and a red towel washed at 158F both ran over their respective loads. But I'm more careful in my use of 158F ("sanitize") now.

I've had bright colored tops with white collars come out with dye all over the collar, discoloring it from washing it in warm water..not to mention, the slight shrinkage warm water sometimes does .
So ever since, I use cold water on bright colors with white trim. Never had a problem with dye bleeding or shrinkage since.

I read this today on the Vaska website and thought it was interesting. As an fyi - Julia Fry who founded Vasaka worked in the fashion industry for years (for companies like Nicole Miller) so she knows fabrics.

My kids have some of those shirts too (darn the Gap) - the hottest temp I use for their colored clothes is warm (since my machine has no heater I'm sure that's not very warm). I've not noticed a problem with greying, however, I do use oxygen bleach products which are color safe on many loads.

Textile Care
From working with fabrics over the years, we've learned a lot about textiles and how to keep them looking and feeling good. Here are some simple, "green" tips to help you take the best possible care of your clothing and linens.

Use cold water wash programs as often as possible. Hot water isn't good for colors or fine fabrics - it won't make them cleaner. For colors and fine fabrics, pre-treat stains with Vaska Spotoff and use Vaska Herbatergent to wash in cold water.

Hang clothing and linens to dry. Avoid using the clothes dryer whenever possible - the largest carbon footprint from doing your laundry comes from washing and rinsing in hot water and using the clothes dryer.

Avoid non-natural fabric softeners and dryer sheets. Most commercial softeners and dryer sheets use chemicals like dihydrogenated tallow dimethyl ammonium chloride, which harm fabrics by coating them or penetrating their fibers.

Here is a link that might be useful: Vaska Home - textile care

Ugh, a shirt ought not run in a warm wash, which isn't much above body temperature. What happens if your kids get hot and sweated up while wearing those shirts, and then they sit on a white chair?

"Hot water isn't good for colors or fine fabrics - it won't make them cleaner."

Meaning no disrespect to Ms. Fry, I completely disagree. Successfully laundering clothes involves the right balance of a handful of basic fundamental ingredients - mechanical action, water temperature, detergent, and time. While hot water may not get your clothes "cleaner" - depending on our definition - it may get them equally clean in a smaller amount of time. Or it may require less detergent to achieve the same results. Increasing the water temperature does make a difference, and regular HOT or SANITARY washes are key to avoiding smelly washer syndrome.

I wash my boys' two-tone & "layered" shirts on warm water with Clorox II with no running problems. It seems to work with no bleeding. I figure if I follow washing instructions when a bright color is next to white that it is designed not to run -- or I'll return it.

I'll also comment on cleaning dingy clothes. We receive nice hand-me-downs from my SIL who must use cold water all the time (as well Dreft when the kids were infants & toddlers -- Tide Free is fine for infants & toddlers). For some reason they were always dingy. I washed with Clorox II & after several washing they look marvelous.

Good luck!

thanks so much maks_2000. that was actually really helpful. i will try clorox 2. we get a lot of hand me downs too!

Use Shout Color Catchers and wash as per care tag instructions...

-Case

Simply unstitch the sleeves and wash them separately, then reattach them when you are ready to wear. ...Just find the fun, and the job's half done!

100% agree with Cancancase. Shout color catchers (color magnets) are amazing! I have used them for years & years.

Myself, and my son have quite a few of these "baseball" t-shirts. 3/4 white sleeves and colored bodies. I wash in warm (which I believe is around 100F) and I use Tide he Powder and a little Downy FS. Shirts looks perfect...wash after wash!

I used the vinegar and a color catcher and tide pod and the water was Black and whites white and color catcher was dark brown. The colors look like the day I bought the shirts,

I also recommend Shout Color Catchers. I use 3 or 4 of them when I wash quilts I’ve just finished. Never had any color transfer issues.