The checking of the of banknotes for soilingThe process of staining, usually by greasy materials sticking to the surface or by the absorption and adhesion of dust and particles to the cotton fibres of which the banknote is made. It is one of the main reasons for banknote deterioration and their subsequent destruction. More, graffiti, limpness, tears, dog-ears, etc. Banknotes that are considered fit will be returned into circulation, while unfit banknotes are withdrawn from circulation.