DFO is responsive to the amino acids present in the body protein. Research has established that DFO will develop 2.5 to 3 times more latent prints on paper items than ninhydrin used alone. If used in sequence with ninhydrin, DFO must be used first to achieve fluorescence, mix it yourself or use the convenient spray. Dip the paper documents or spray them and allow them to dry, heat the papers using an oven or dry iron for 10-20 minutes. Examine with a Forensic Light Source and photograph the resulting latent prints, heating the papers with a hand iron for 10-20 minutes is a bit time consuming. Priced and sold per gram.