I did some break tests with an unexpected result. I alternated snapping Gutterman and some Coats & Clark I picked up at Walmart. Both were polyester and I did enough snapping to make my hands sore and use up several yards of each type of thread. The Gutterman has a nicer appearance, smooth and little or any fuzz. The C&C is pretty generic looking and a little fuzzy. However, after snapping a lot of thread I had to come to the conclusion that the plain old generic C&C was slightly stronger than the Gutterman. I think the Gutterman quality control is probably better and there would be less variability between each lot of thread than with the C&C, but I found the results to be very surprising. I really expected the Gutterman to be noticeably stronger and that was not the case.
"To turn from this increasingly artificial and strangely alien world is to escape from unreality. To return to the timeless world of the mountains, the sea, the forest and the stars is to return to sanity and truth." --Robert Burnham Jr.
I have no doubt someone uses kevlar and spectra thread to good advantage. But I don't see the need for it gear making. First off... I don't want to run a rasp through my machine. Why would I want to use thread that is stronger than the materials the tension plates are made out of? Secondly... I am of the opinion that you stitching should be the weakest link in the chain. Please I did not say it should be weak. I said it should be the weakest link. I would rather have a few stitches snap than have the fabric tear out in the back. One you can fix with a small sewing kit. The second... who knows.
I may be slow... But I sure am gimpy.
"Bless you child, when you set out to thread a needle don't hold the thread still and fetch the needle up to it; hold the needle still and poke the thread at it; that's the way a woman most always does, but a man always does t'other way."
Mrs. Loftus to Huck Finn
We Don't Sew... We Make Gear! video series
Important thread injector guidelines especially for Newbies
Bobbin Tension - A Personal Viewpoint