sometime the pulp must undergo a ''pulp laundering'' operation call deinking (de-inking) toremove printing ink and ''stickies''
(sticky materials like glue residue and adhesives.) Papermakers often use a combination of two deinking processes. Small particles of ink are rinsed from the pulp with water in a process called washing. Larger particles and stickies are remove with air bubbles in another process called flotation . During flotation deinking, pulp is fed into a large vat called a flotation cell,where air and soap like chemicals call surfactants are injected into the pulp. The surfactants cause ink and stickies to looseen from the pulp and stick to the air bubbles as they float to the top of the mixture.The inky air bubbles create foam
or froth which is remove from the top, leaving the clean pulp behind.