Laundry: red and white on same article

Soaking in salt water is an old trick to set dye, but it doesn't work with all modern dyes.

The manufacturer could probably tell you how to wash the shirt. He could tell you to use a dye magnet. It's a sheet you toss into the washer to grab any dye that bleeds into the water. It protects whites. It can also protect colors from being dulled by other colors.

Cold water reduces bleeding. Sometimes bleeding occurs after laundering if the clothes are left in a damp heap.