Peckish

Aw, that's sweet of you to say. I'm always full of something, that's for sure.

I have not yet used this method on batiks. I wouldn't hesitate to, however.

I start the bleeding fabric off in water that is 140° F and let it cool overnight. Drain and test it by rubbing it with a white cotton towel or paper towel. I've never had a fabric bleed after letting it sit overnight.

I usually test my fabrics before using them in a quilt, so I've not dealt with a whole quilt top. However, I did have a problem with a single block, and this is one time that I did use a color catcher. The block was white with black and red applique. The red fabric was a piece I had purchased years ago when I first started quilting, before I tested my fabrics. I discovered after starching my block that the red fabric was a bleeder, and it was bleeding into the white background. Before it could dry, I put it in the kitchen sink with very hot water and grabbed a color catcher. I mashed and squished and rubbed the color catcher on the white areas that had absorbed some of the red dye, then I mashed it on the red fabric itself. All of the red dye came out of the white fabric except for directly behind the red applique.

My information comes from the experience of a couple other quilters. Vicki Welsh dyes her own fabric and did a series of experiments about setting dyes that you can read here and here. Margaret Solomon Gunn is an award-winning quilter who had a disastrous experience with a gorgeous quilt that bled when she tried to block it. Her fabrics started bleeding, so she pinned color catchers to it and soaked it. Then her pins rusted. Her story is here.

Hope this helps answer your questions!