***
*** Aurifil does make an 80 Wt.
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*** Pull up Bree123 's link.
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*** It shows it is Egyptian cotton.
***

Pat Sloan blogged about it in August 2016, she loves it for applique.
http://blog.patsloan.com/2016/08/tim...ncredible.html

I use 80wt thread when making a wall hanging that I know will never be washed. It is especially good for making miniatures as it adds no bulk to the seam and you can get a really nice crisp fold if paper piecing. For a quilt that will be used on the bed...NO.

Also, would be good anywhere that you may want to use invisible thread. Great for raw edge applique.

Well, I use Aurifil 50 wt. almost exclusively for my quilting because it is an amazing thread -runs smooth as glass through my machine and never breaks or tangles. My curiosity up, I put in a search for Aurifil 80 wt. and not only did I find it, it is available in my absolutely favorite online place to shop for quilting material -especially precuts. It is available at Fat Quarter Shop, and this weight is specifically for APPLIQUE quilting, both hand and machine. The Shop seems to have several color-coordinated sets and even has an Aurifil Applique Thread Monthly Club, so it must be popular among those who applique thread.

Given the high esteem in which Aurifil thread is held, I suspect you just got a bad spool.

Good luck!

My thread and post were before the new Aurifil 80 wt and the other 80 wt and 100 wt threads were available for machine quilting. A new manufacturing process was developed to make the thin thread strong enough for machine quilting. Every good brand of thread now has the thin thread available.