Another tshirt quilt question...
 

Hi! I have the interfacing ironed on to the backs of my shirt squares. How much interfacing should be left around the edges? I saw a pic in which the person left about a 1/4 inch - what happens to that when you sew the shirts to sashing or to each other? I'm thinking I need to cut the interfacing to be the exact size of the tshirt square???

My understanding was that you should iron the T-shirts to the interfacing before you cut the T-shirts to size. That would mean there wouldn't be any interfacing left around the edges.

That's right, dunster. Apply a piece of interfacing larger than the square you plan to make to the shirts before you cut them.

I ironed on my interfacing and then cut them to size. I didn't have any overhang at all

Perfect. That clears it up! Thanks.

That is how I did it. You want that interfacing in your seam to keep the t-shirt from stretching. That is the major reason why you attach the interfacing to the t-shirt in the first place.