Formation Agents are used in Nagashizuki (Japanese style) papermaking. It is essential when using the Japanese fibers and can be used with Abaca to form a thinner sheet. It separates the long bast fibers and slows drainage through the mould. They are synthetic substitutes for the tororo-aoi plant. There are two types, PNS and PEO. PEO is used under most conditions when other papermaking chemicals are present, such as retention aid or methylcellulose. PNS is used where no other additives are present.