I’ve been experimenting with silk, rayon, nylon, triobial poly, normal poly, cotton, denim, and different thread companies. Like Buddy Jim, I like these thread types, but I’m still experimenting.
Just a warning, silk is CRAZY expensive. I forgot the exact amount, but It’s something like $5 for 100 yards. The best(In terms of play) poly thread I’ve found is $3 for a spool of over 2,500 yards.
But poly is an overall good yoyo string, it’s strong, whippy, soft, and lasts a long time. Other threads vary, some companies of, lets say, cotton make their cotton rough, some make their cotton soft-just keep experimenting with different thread types and companies and you’ll find a company that makes their thread just the way you like.
To everyone who is starting to make yoyo string, I gave mlewis38 some tips earlier: