Starburst is one of the standard response types.Some yoyos using the starburst response are Loop 1080, LP, Vortex and Fireball.

Fireball (YOMEGA)

When the string touches the sharp ridges the yoyo comes back.

The starburst has this characteristic “The friction caused by starburst makes Poly 100% string melt and shred”

However, some yoyos that use a starburst response can stil use poly 100% string, for exmaple vortex.

some 2A players compete using poly 100% string with starburst response yoyos.

Why?

*This article is written from our personal experience.if you have professional knowledge that contradicts this information, please let us know.

Polyester String doesn’t suit looping?

With looping the yoyo is constantly going up and down the string, therefore the string must be strong.

Cotton 100% string is weak and will break quickly with modern yoyos.
to make a stronger string, we blend 50% Cotton and 50% Polyester.
Therefore Polyester is a stronger choice for yoyoing.

Duncan Cotton String, Type6 50/50 String, Kitty String

There is not much of a difference in feeling between 50/50 and Poly 100% string.

if poly 100% string is so strong and feels the same, isn’t it better for looping?

The reason Poly 100% string breaks while looping.

Using one looping model poly 100% string breaks often, but 50/50 string does not.

Poly 100% string melts and breaks due to the strong friction of the starburst response and the narrow gap.

Will the string be stronger if there is less friction?

These photos are a comparison of Loop 1080,  which works better with 50/50 string,  and Vortex, which works better with poly 100% string.

Loop 1080 (YoYoFactory)

Vortex (YoYoJoker)

With Loop 1080, you can see that the ridges of the starburst are higher above the spacer than with Vortex

Furthermore Loop 1080 has an adjustable gap system, so the gap can be extremely narrow.

Loop 1080 with its most narrow gap setting

Actually, Loop 1080 with its most narrow gap setting, combined with poly 100% string creates a super strong friction that can break the string.

However, even with the same setting, just by switching to 50/50 string, the string won’t break.

How to weaken the friction.

If the ridges of the starburst are less pronounced above the spacer, the friction will be weaker.

We tested several models with poly 100% string (Kitty String Poly 100% Normal) and 50/50 string.

Loop 1080 + Yomega Delrin Spacers (Black)

LP

Crook

We replaced the spacers in Loop 1080 with YOMEGA Delrin spacers (Black).

YYF Spacer (Short), YOMEGA Delrin Spacer Black (Taller), White (Tallest)

[Result] With that setting, neither poly 100% nor 50/50 string was prone to breaking.

*The tester was a competiton-level 2A player but not world champion level.
*The results could be different with a higher-level player.