Sudan Black

Sudan Black

Sudan Black is a dye that stains the fatty components of sebaceous secretions to produce a blue-black image. While it is less sensitive than some other latent print development techniques, it is particularly useful on surfaces contaminated with greasy or sticky substances. Use on nonporous surfaces such as glass, metal or plastic materials and waxy surfaces such as candles or wax-paper milk cartons. It is easy-to-use, inexpensive, non toxic,and has an indefinite shelf life.

Shelf-life of Sudan Black powder: indefinite. The working solution also has an indefinite shelf-life.

Technical Note:

It works best on glass, metal or plastic materials. It can be used on waxy surfaces, such as candles or wax-paper milk cartons. Sudan Black is a dye which stains the fatty components of sebaceous secretions. Besides being sensitive to grease, oils and sticky substances, it will also enhance glue-developed latent prints.

We have reports that this process works very well on the inside of latex gloves. First, the gloves must be treated with glue fumes, quite a bit heavier than normal. Dip the gloves in the solution of Sudan Black for about ten seconds and rinse in water. Continue to dip for ten seconds and rinse until latent prints appear. Often, latent prints will have better contrast after the surface dries.

As with any new chemical process, read and understand the Material Safety Data Sheet on all of the chemicals involved. Practice normal industrial hygienic procedures of wearing lab coats, protective gloves, and goggles, if there is any risk of splashing the solution into the eyes. If the solution is going to be used for long periods of time or on large surfaces, it is recommended that it be done in a fume hood or with adequate ventilation. The process of Sudan Black is easy, inexpensive and nontoxic. It can be a bit messy so use some common sense regarding the area you are working in to make the clean up easier.

Do not use this on porous or absorbent items as the entire item will be stained a dark color. This process may run inks, and interfere with blood and body fluid examinations.

Comparison and Identification of Fingerprints by James F. Cowger Manual of Fingerprint Development Techniques by the British Home Office, second edition