Technology is at the heart of the manufacturing process of banknotes with highly specialised machinery for the high quality and security standards which are crucial in the fight against counterfeiting. The manufacturing process includes factors which can produce variations in the banknotes. For example, variations occur when more than one piece of equipment is used for the same task. The evaluation and validation of the quality of the sheet and all the resulting banknotes represents a major challenge. Taking watermarks and other security features as examples, this presentation proposes a control strategy for the validation of product conformity.