I piece and quilt with Aurifil 50, but I use different sizes of needles for each - larger for quilting. I do sometimes use polyester thread for quilting if I want a particular color or a thicker thread (e.g., Mettler or Connecting Threads cotton) if I want a particular look.

I piece with 50 weight, generally Aurifil. My favorite machine quilting thread is Coats & Clark machine quilting thread 30 weight which is a cotton thread. I've never had breakage with it and it is economical. Another plus is that one of the places it is sold is Walmart which is a few miles from my home as opposed to a quilt shop or JoAnn's which is 30 miles away so if I run short it's not a problem. My Janome machine does not like Coats & Clark Dual Duty thread in the top. I can use it in the bobbin and so have been using up my odds and ends that way.

I am using coats and clark. I should clarify. It isn't breaking in the machine. The quilt is on my bed and I'm noticing little breaks here and there. It doesn't seem to be wearing well. Happening after the quilt is made. It is brand new thread.

Cotton thread is traditional because when vintage quilts were created, cotton was all that was available. I personally prefer polyester thread for machine quilting because it is stronger and creates less lint for my machine.

There are multiple reasons why cotton thread might break after FMQing. One is the type and brand of thread. Some brands are better than others. Also, cotton thread can be stronger or weaker depending on the type of cotton in the thread (shorter or longer strands), how it is wound, weight, and ply (number of strands). Distance between quilting lines is another variable. Longer distances mean that more stress is put on individual threads when someone sits on a quilt, for example, or when the quilt is handled while heavy with water after washing. (Water adds a *lot* of weight to a quilt, which is one reason why you really do not want to hang a wet quilt on a clothesline.) Stitch length can also affect how much stress a thread can take, with long stitches breaking sooner than short stitches.

Not all cotton quilting threads are a like. The higher end long staple egyptian cottons that are manufactured properly will be the ones you hardly have breakage on and there are very few of these imho i got breakage on many name brand cotton threads that are popular. If it is true egyptisn cotton thread it will not be cheap and will cost quite a bit

My quilting instructor of the first quilting class I ever took in 2006 and that got me hooked on quilting, recommended the book, "Machine Quilting Made Easy" by Maurine Noble, published by That Patchwork Place. The book is an excellent reference for its many charts showing which type of thread, weight of thread, type of needle, size of needle, etc. to be used together for best results. The book can be found on Amazon.com and you can "look inside" to see what the charts look like. I wouldn't be without this reference book.

I do not use 100% cotton thread for the quilting as I find that the thread will break when the quilt is used.

I have used both..cotton seems to break more....Yes, yes...I have heard all cotton thread with cotton fabric...but I do not make Heirloom quilts....I try to make quilts that are used every day.