Reagent
Gun Blue
DISCLAIMER: Gun Blue solutions will not work on lacquered steel cartridges. Cartridges must be made of nickel or brass metals.
1. Lightly fume cartridges with cyanoacrylate ester.
2. Immerse cartridges in Gun Blue solution.
3. Gently stir, roll, or agitate the cartridges in the Gun Blue solution for 10 – 15 seconds.
4. Monitor closely for development (ridge detail may develop quickly and cause over-development).
5. Halt development by immersing cartridges in distilled water for 2 minutes.
6. Allow cartridges to air dry.
7. Ridges will develop a black color and can be captured using 1:1 photography.
View under
Normal Vision
Goggles / Filter
None
Development Color
Black
PRO TIP: To optimize development of ridge detail on brass cartridges, Sullivan suggests to process with cyanoacrylate esters followed by Gun Blue followed by Basic Yellow 40 dye stain.
REFERENCES
Arkansas State Crime Laboratory. (2017). Gun Bluing Technique with Cartridge Casings. Latent Print Section Quality Manual. p. 39-40. Retrieved from https://www.dps.arkansas.gov/wp-content/uploads/2020/05/Latent_Prints_QM.pdf
DEA Office of Forensic Sciences. (2020). Gun Bluing Solution. Latent Print Examination Manual. Retrieved from https://www.dea.gov/sites/default/files/2020-05/2020%20Latent%20Print%20Examination%20Manual%20DEA.pdf
SULLIVAN, K. J. Optimized Development of Latent Fingerprints on Unfired and Fired Brass Cartridge Casings. Forensic Science Internship, Marshall University, West Virginia, USA.