I got very lucky
A few weeks ago I starched my backing fabric overnight like I usually do.
Didn't pre-wash. It's a white fabric with grey, black, red and blue printing.
Never thought this would bleed. When I ironed the fabric the next day
I noticed that the red had bled. Yikes. Too late. Since I was making this
quilt for myself I didn't want to wash and start all over. So I just carried on
and quilted then washed it with some color catchers. Lo and behold
the red bleeding is gone. Happy dance.
I never thought it would go away because I ironed the fabric more than
once...with starch then when I glue basted my quilt sandwich.