Backing Fabric vs Quilting Cotton Fabric
 

Please can someone explain how 100% cotton backing fabric is different than the 100% cotton fabric we use for piecing a quilt top?

The tightness of the weave and the weight of the threads can be different. I used to see a lot more coarsely woven wide width backs than I do nowadays, so my Jinny Beyer back felt much different than the regular width yardage.

I sort all fabric on a piece by piece basis with no regard to brand by feel. I've had high priced name brands from LQS turn into a crummy rag after washing, I've had lower brands that behaved superbly despite their humble beginnings.

Mostly it is the same.....I often use yardage pieced together to make a backing. You can also buy "backing" that instead of the usually 42 inches wide fabric is about 108 inches wide so you don't have to stitch lengths of the regular 42 inch wide stuff together....I have noticed that some of the 108 inch wide stuff doesn't seem to be as good quality as the other and sometimes it is more crooked and I have to waste fabric straightening it up so I have learned to purchase at least a half yard extra when I have purchased it....Mostly I have gone back to just buying the 42 inch wide stuff and stitching lengths of that together to make my backing.....

If I am making a scrap quilt|, I like to use up large pieces of fabric for my quilt back to give it a scrappy look also.

You can use it in a scrappy quilt if the weave has the right "feel" to it. If it has a looser weave you may want to reconsider using a particular piece. So much depends on the weave.

So much will depend on the weave of the fabric. I try to be more careful now when I am buying backing fabrics. I have been known to return a piece I purchased on line because the weave was not as tight as I wanted it. This is one of those you learn as you go and develop your own preferences. I still use both as both a looser weave and a tighter weave work well for a backing. I am just more careful on how much I buy. I do not need to have extra of a fabric I will not be using in another quilt top or can't use in a scrappy quilt.

I really didn't know there was much of a difference. When I make my backings, I just piece big pieces of fabrics and usually fabrics from the front of the quilt.

There should be no difference, but that being said, each fabric is different. I do QAYG and so I make scrappy backs, planning out what back fabric I use for each square. Sometimes I like the back as much as the front side. And I wash my fabric before I bring it into my sewing room. I want to know how it washes and dries before sewing anything.

It's much wider, also. Quilting fabric is 42" to 44" wide, backing runs from 90" to 108" or even 110".