▁ ▁When ▁kn itting , ▁some ▁kn it ters ▁enc lose ▁their ▁balls ▁in ▁j ars ▁to ▁keep ▁them ▁clean ▁and ▁un t ang led ▁with ▁other ▁y ar ns ; ▁the ▁free ▁y arn ▁passes ▁through ▁a ▁small ▁hole ▁in ▁the ▁jar - l id . ▁ ▁A ▁y arn ' s ▁useful ness ▁for ▁a ▁kn itting ▁project ▁is ▁jud ged ▁by ▁several ▁factors , ▁such ▁as ▁its ▁lo ft ▁( its ▁ability ▁to ▁trap ▁air ), ▁its ▁res ili ence ▁( el astic ity ▁under ▁t ension ), ▁its ▁was h ability ▁and ▁color fast ness , ▁its ▁hand ▁( its ▁feel , ▁particularly ▁soft ness ▁vs . ▁scratch iness ), ▁its ▁dur ability ▁against ▁ab ras ion , ▁its ▁resistance ▁to ▁p illing , ▁its ▁hair iness ▁( f uzz iness ), ▁its ▁t endency ▁to ▁tw ist ▁or ▁un tw ist , ▁its ▁overall ▁weight ▁and ▁dra pe , ▁its ▁blocking ▁and ▁fel ting ▁qual ities , ▁its ▁comfort ▁( bre ath ability , ▁mo ist ure ▁absor ption , ▁w ick ing ▁properties ) ▁and ▁of ▁course ▁its ▁look , ▁which ▁includes ▁its ▁color , ▁she en , ▁smooth ness ▁and ▁orn amental ▁features . ▁ ▁Other ▁factors ▁include ▁aller gen icity ; ▁speed ▁of ▁dry ing ; ▁resistance ▁to ▁chemical s , ▁moth s , ▁and ▁mil de w ; ▁mel ting ▁point ▁and ▁fl amm ability ; ▁ret ention ▁of ▁static ▁electric ity ; ▁and ▁the ▁prop ens ity ▁to ▁become ▁st ained ▁and ▁to