Whitening agent ke mofuta oa motsoako oa manyolo o ka ntlafatsang bosoeu ba lesela la fiber le pampiri.E boetse e tsejoa e le optical brightener, fluorescent brightener.Masela, joalo-joalo, hangata a mosehla ka lebaka la litšila tsa mebala.Nakong e fetileng, bleaching ea lik'hemik'hale e ne e sebelisoa ho li tlosa mebala ka ho eketsa lisebelisoa tse soeufatsang lihlahisoa.