I but the two edges together and use a wide zig zag stitch.. and a bit longer stitch length. It amazing how much usable batting you can recover from trimmings.

Tried this yesterday-quilting a quilt on my longarm frame, using pieces of batting up, I laid a piece over the first, cut along the second piece edge, then using my Elmers washable glue stick, applied glue to the backing piece, enough to cover both edges of batting, pressed them together at edge, let dry overnight. This morning they are stuck tight, no gaps, no sewing, think i'll use this method again. Best of all, the glue will wash out!!

Thanks, I will give it a try on a smaller wall hanging before I try a large quilt. I appreciate your feed back.

Another way to join pieces of batting is flatlocking (done on the serger). The pieces lay nice and flat. I like the batting tape, too.

I lay the pieces on top of each other and trim. Keeping the pieces together as I had cut them, pin and sew using a blind hem stitch. Open it up and smooth out the seam with your finger. I find it easier to handle large pieces without having gaps in the stitching. I did a small piece the other day for a table runner butting them up together and using zigzag, but I had to go over several areas where it pulled apart. I have much better luck with the blind hem way.

I also use the zig zag stitch. It works well. My problem is that I simply have no patience for sewing batting together so I just keep it smushed in big tubs. I've been piling up quilt tops in anticipation of getting a long arm though so I probably should put together batting pieces at least for my first few attempts at quilting on the long arm.

One more thing I probably should do but probably won't....

I use the batting tape these days but before that I used computer paper, unwaxed lunch paper or any paper I could cut into long strips.

If want a good join. Over lap for a small amount. Then cut down in the overlap this will make sure both edges match. I leave in place after cutting carefully remove the surplus from the top and use the binding tap or you can hand whip stitch. Once joined turn over and remove other surplus but I keep these pieces as they are great for stuffing tops etc.