▁These ▁are ▁added ▁in ▁the ▁wet ▁end ▁of ▁the ▁paper ▁machine ▁to ▁improve ▁ret ention ▁fine ▁particles ▁and ▁fill ers ▁during ▁the ▁formation ▁of ▁paper . ▁Ret ention ▁a ids ▁can ▁also ▁be ▁used ▁to ▁improve ▁the ▁ret ention ▁of ▁other ▁pap erm aking ▁chemical s , ▁including ▁s izing ▁and ▁c ation ic ▁st arch es . ▁The ▁improved ▁ret ention ▁of ▁pap erm aking ▁furn ish ▁components ▁impro ves ▁the ▁oper ational ▁efficiency ▁of ▁the ▁paper ▁machine , ▁reduces ▁the ▁sol ids ▁and ▁organ ic ▁loading ▁in ▁the ▁process ▁water ▁loop , ▁and ▁can ▁lower ▁overall ▁chemical ▁costs . ▁ ▁Typ ical ▁chemical s ▁used ▁as ▁ret ention ▁a ids ▁are : ▁poly ac ry lam ide ▁( P AM ), ▁poly eth yl ene im ine ▁( PE I ), ▁col lo idal ▁sil ica , ▁and ▁bent on ite . ▁ ▁See ▁also ▁Col our ▁ret ention ▁agent ▁ ▁Category : Process ▁chemical s ▁Category : P ap erm aking <0x0A> </s> ▁Zel andom y ia ▁is ▁a ▁genus ▁of ▁c rane ▁f lies ▁in ▁the ▁family ▁Lim oni idae . ▁ ▁Distribution ▁New ▁Zealand ▁& ▁Chile . ▁ ▁Species ▁Z . ▁ang usta ▁( Alex ander , ▁ 1 9 2 3 ) ▁Z . ▁arm ig era ▁( Alex ander , ▁ 1 9 4 5 ) ▁Z . ▁at rid ors um ▁Alexander , ▁ 1 9 3 2 ▁Z . ▁cin erei ple ura ▁( Alex ander , ▁ 1 9 2 2 ) ▁Z