Here are some tests on a range of maroon colored polyester shirts. This is the test explained earlier, a drop of plasticizer and then a white fabric heated to 320 degrees F for 30 seconds.

The nine shirts are a spectrum of results. Even shirts that don’t have much of a dye migration problem do give off some dye. In this range, the first shirt probably could be printed with any white ink. Then the next couple would require a polyester ink. The last four or five and definitely the last two will need a dye blocking grey undercoat before any white is put down