One of the worst parts to quilting is having waste. Batting is the worst of them. A few inches there a foot here... all trash. Rewind... all usable! All it takes is stitching them together.
In the move to my new house my sewing machine shaft has going missing. I would typically use 100% cotton or 80/20, but I don't have any scraps on hand so I'm stuck with this thin poly. I am just hand stitching much looser than if I was using this for a project. You will get the idea though.
Before you start, refer to the batting instructions for the suggested width of quilting. If it is 3"- 5", then the pieces of batt should be no smaller than 6" each. Essentially whatever the suggested width of quilting is, add an inch. By doing this it will help stabilize the batt since you will have some quilting on both piece.
First take your pieces of batting that are the most similar in size. If the edges are straight, rip some of it off... you do not want a nice even straight edge.
The next step is as easy as the first. Butt the edges up against each other. You don't want it to be straight seam.
Using the widest zig-zag possible on your sewing machine to stitch together side by side and not on top of each other. If there is a few place where it has overlapped that is okay. For the most part you don't want that.
If you are joining pieces horizontal and vertical the process is the same. Just the opposite direction.
It is easy as that. To answer the questions swirling around in your mind... "Why don't you want nice even edges?" or "Why not overlap the pieces?" Here's the answer:
If you over lap them, depending on how it is quilted the seams will show up bumpy once it is finished. If they are sewn side by side, without being overlapped it will become weak overtime. So to prevent this when the pieces are uneven sewn together they will be stronger and less likely to pull apart.
I hope this has been beneficial to you. If you have a question leave it in the comments section on the Tips & Techniques home page.