Hi,
I’ve been wondering what the best string to use for 4a yo-yoing is. Whenever I use 100% poly it’s too slippy. Is 50/50 the best? ??? I’m also using an ORIGINAL Fiesta so that might make a difference.
Thanks 
For all my 4a throws I use regular kitty string. If your binds keep slipping you can try thick kitty string. It takes a bit to get perfect binds at first, make sure your binding according to the spin on the yoyo to make it easier also.
I hear 50/50 is used because it offers more response.
I have a new fiesta so, were as close as it gets here. 100% poly works for me. Just work on your binds. Make sure your having enough string going into the gap, and you have a sort of rotation of the yoyo as you’re binding. Ben condes tutorial has helped me help some people.
regular poly should work fine. I’ve occasionally had trouble doing one hand binds using it, but it’s not impossible. Thick kitty is also great.