Collaborative study of accelerated development of latent fingerprint images on paper by application of steam

Nine latent fingerprint examiners participated in a collaborative study in the use of a steam iron to accelerate chemical development of latent images on bond and newsprint papers treated with a 0.5% solution of ninhydrin in acetone. Four latent images were placed on each paper by the Associate Referee during an 8 hr period. The papers were paired and numbered 1, 2, and 3. Three pairs were mailed to each collaborator who treated Pair 1 by dipping, Pair 2 by brushing or swabbing, and Pair 3 by spraying. After air-drying, the papers were subjected to heat and steam from a household steam iron until the images developed. The average time for developing all images was 5.8 min/paper. Of the total images available, 92.1% were developed to some degree; 47.9% of these images or 43.5% of all images were identified by the collaborators. The method has been adopted as offical first action.