I made a king-size t-shirt quilt with no interfacing. Each knit segment was stabilized with woven fabric sashing
strips. The whole thing was pinned securely then machine quilted. The knits haven't stretched at all.

I am not familiar with the technique, but the technique in the TOO COOL T-SHIRT QUILT book by Andrea Funk doesn't use any interfacing. I have yet to find a copy of the book, except online, but it might now be found in libraries.

When I do t-shirt quilts for customers, I use a fusible tricot. It's lightweight and isn't stiff at all.

Hi Jan I have made memory quilts for customers using a loved ones clothing and I used a knit fusible interfacing it stabalizes the t-shirts but does not make it stiff. I usually run the grain lines opposite each other. Joan

My Mom is starting a tee shirt quilt. I think some interfacings might be too stiff. Any advice? Thanks, Jan