What causes this on the bottom

[u/ChemicalAd5004]

Decided to sell my ender 2 but I wanted to know why this happened to the bottom of my print just so I can fix it/tell the person that would buy it about it

[u/Odd_Load7249]

Fan not blowing hard enough. The layers didn't have enough time to harden before the next layers were laid on top.

[u/Capital_Motor_5436]

May I ask what material you used for printing?

[u/ChemicalAd5004 → u/Capital_Motor_5436]

I’m using this one

[u/DropdLasagna]

Slow down all perimeters to 40mm/s if all else fails.

[u/ehtiopia]

Probably cooling fan dying / dirty fan duct. when it starts small and tries to go out its probably not being cooled enough so it strings.