--This is a rough estimate for a large lap-sized quilt. You may need more to make a quilt large enough for a bed.
--You can make all the blocks the same size (say, 15" squares) or use all different sizes like I did.
2. Iron a lightweight fusible interfacing to the back of your shirts according to the manufacturer's instructions.
--I chose lightweight interfacing because I didn't want the t-shirts coming out too stiff to snuggle under.
--I'm sure you would never do this, but DO NOT iron directly on the printed part of the t-shirt. It will melt! I made that mistake with one of my favorite shirts from college... So sad. :(
3. Lay out your t-shirts in a pattern you like. You will most likely need to use some t-shirt scraps backed with interfacing or some other fabric to fill in gaps in your quilt top.
--I put my largest pieces in the corners and filled in the spaces from there.
--Squaring off the edges after you've applied interfacing will help you get the best shape from your shirts, and you will secure the interfacing as you sew each seam. This means you won't have to quilt over each shirt if you don't want to.
5. Sew blocks together using a 1/4" inseam and a jeans/denim needle (100/16). You may have to sew up a crazy seam or two, so be ready for it. See instructions for this kind of seam below...
6. Add a border if you'd like one.
--I used quilting cotton for mine.
7. Baste, quilt and bind your quilt as desired.
--When basting your quilt sandwich, try not to pin the printed part of your shirts too much because it could leave holes.
--I quilted in the ditch (right on top of each seam) with a neutral thread to preserve the look of the shirts.
**This is just the process that I used. I do not claim to know everything there is to know about t-shirt quilts, but it worked well for me! :)
Instructions for sewing a jagged seam: