Bree123

Wow! Speaking as someone who only uses cotton in her quilts, YOU ARE A REAL QUILTER. I don't care what fabrics you use.

Okay, that said, there are a few things to consider when selecting fabric:
1) I have seen & carefully studied what has happened to poly-cotton fabrics from 50 years ago. The polyester & cotton fiber eventually start to separate. The polyester is stronger, so it will slightly pull on the cotton over a very long period of time & eventually you will see some of the cotton thread in the fabric start to snap or buckle. I realize that polyester fibers have improved since that time, but it's still going to happen to some extent.
2) Polyester or poly-cotton blends are not recommended for baby quilts because of what happens if they catch on fire. Cotton turns to ash. Poly turns to molten balls of plastic. It typically means the difference between 2nd and 3rd degree burns. (If you use a heating pad while in bed, you also don't want a poly bed quilt.)
3) For longevity, it's generally best to stick with one fiber -- do everything either in only cotton, only wool or only polyester.
4) Polyester fabric & the poly- part of poly-cotton will pill. Cotton doesn't pill.

Polyester is plastic so yes, in a sense it will live forever (just like all those plastic bags floating out in the ocean). But over time with wear-and-tear, stitches will sometimes snap because they seem to bunch up together more in the wash. It seems to be the general consensus that well cared for poly fabrics/threads will last 80 years or so before they start to break down. Well cared for cotton fibers generally start to break down around the 20 year mark.

One other thing... all poly fibers are not the same. I haven't researched them well enough to know how to pick one, but there is information on the web to help understand which types of polyester might be best suited for a bed quilt.

Good luck with your project!

Peckish

First of all, I don't agree with the premise of your statement. I am a "true quilter" and a "real quilter" (whatever that's supposed to mean) and I use polyester thread. I don't use poly fabric because I personally don't care for it. I find it itchy, hot, sweaty, and in case of fire, it's not the first thing I'd like to have next to my loved ones' skin. That's my opinion and it's worth exactly what you paid for it.

Second of all, there are many, many older quilts where it's been documented that the very first thing to start deteriorating was the cotton thread used to piece and quilt them. The older cotton threads were susceptible to dry rot.

However, technology marches forward, and both cotton and poly have improved over the years. I don't get bothered about whether my quilts will last for a hundred years or not. If they last, they last. If they don't, then more opportunity for me to make new ones to replace the old.

Friday1961

As a long time garment maker (who at one time made a lot of double knit clothes! ) but a novice quiltmaker, I inadvertently mixed a poly/cotton with 100% cotton in a quilt when I first began piecing. I was horrified when I realized what I'd done, but my cousin, a long time quilter, told me not to worry, there were "no rules". That top, a queen size and too much of a struggle for my DSM, has yet to be quilted so I have no idea how it will look when finished, but I now buy only 100% cotton for quilt tops. But I do use poly batting, mainly because an experienced online quilter advised using it as the easiest for beginners. I like it. I also use poly/cotton thread for piecing and for machine quilting.

crafty pat

My DM used poly and poly blends in a few of her quilts and the ones I have of her's that she used them in have done very well and are still very pretty. I have never used any in the ones I have done.

misseva

My mother used scraps from garment making in her later quilts and they are holding up very well. I do note that some of the poly blends do pill. I also started out using scraps from my own dressmaking as well as those given to me by mother. I try to only use cotton now because, like others have said, it's hard to get a crease in blended material. And cotton really does handle differently than blends. It doesn't 'crawl/slip' like blends do. I have a lap quilt made out of double knit that was given to my step dad approx. 30 years ago and it still looks like it did when it was new and is very warm. I have a full size quilt made out of double knit made by my mother in law - beautiful - looks new ---- but too hot/heavy for me to sleep under. It would be nice at a ball game.