I agree with following the instructions on Vicki Welsh's site. She is a hand-dyer and did a LOT of experimenting and testing to find the best way of setting bleeding fabrics. I have used her method successfully several times for bleeding tops, it really works.
Here is a link to her helpful instructions:
https://www.colorwaysbyvicki.com/upl...edingquilt.pdf
Please note she specifically says to NOT use Retayne or Synthropol.