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Ardrox Dye Stain (The following article is reprinted from the Oct/Dec 1995 issue of the Texas Division I.A.I. newsletter)
by JOE MABERRY ABSTRACT: The use of a fluorescent dye stain to enhance a latent print developed with cyanoacrylate ester fumes is often the only technique which readily makes the latent print visible. The fluorescence must be accomplished with a light source specific to the fluorescing wave length of the dye stain utilized. Ardrox is a fluorescent dye stain that will fluoresce in the 365 nm range of long wave ultra violet light. All agencies should have a long wave ultra violet light source available. A problem one may encounter in photographing a fluorescing ardrox print is the “washing out” of the latent print on the photographic negative. This “washing out” is a result of fluorescence in the non-visible ultra violet range from either the ardrox dye stain or the background substrate. Two effective methods to photographically eliminate this excess fluorescence is to either, A. Use a barrier filter, Kodak 2E, 2A, 2B and black and white film or, B. Use color film. In either case the fingerprint ridges will be white and should be photographically reversed. Aluminum foil was used as an outside wrapping on a brick of cocaine. The latent print processing protocol I used was: 1. Visual examination 2. CAE 3. Visual examination 4. Ardrox dye stain 5. Visual examination with ultraviolet light 6. Black fingerprint powder 7. Visual examination Very little ridge detail was observed after the CAE processing. The visual examination of the Ardrox dye stain with a portable long wave ultraviolet light source produced dramatic results. An identifiable palm print became readily visible.
Using the “old photographer's axiom”, that “if you can see it, you can photograph it” and “what you see through your SLR is what you get”, the dye stained aluminum foil was placed on the MP4 copy stand with a 365nm long wave ultraviolet light source to excite the fluorescent dye stain. A 35mm SLR camera was used for the photography. Very good ridge detail was observed through the camera. A 100 ISO TMAX black and white film was chosen to record the latent print. When the film was processed and printed, the resulting latent print image was not as good as the original image observed through the camera. The latent print was re--photographed with Technical Pan film. Again, the resulting image was not as good as the original. The latent print was then re--photographed with 100 ISO color film. The resulting image was now as good as the original. The question now became, the axiom of the “old photographer”, why wasn't the image on black and white film that of which I saw through the camera -- “what you see is what you get.” The answer is that the phenomenon observed in the photograph is a result of the magic of photography; what you see is what you get, plus what you might not see. When the light source transmits the radiation necessary to excite fluorescence, there is some radiation or light not used in the fluorescence. This light is reflected from or transmitted through the substrate as residual radiation. If it is not removed, it will record on the film. A barrier filter is placed in front of the camera lens to prevent this residual radiation form causing an exposure. An efficient barrier filter absorbs all of the light from the transmitting exciter source and transmits only the wavelength of light evident as fluorescence. The barrier filter eliminates excess fluorescence. For black and white film, a Kodak 2E, 2A, 2B, is a recommended and effective barrier filter. The color film did not result in the same washing out, excessive fluorescence, as the black and white film did because of the recording properties of color film. The color film is more sensitive to the blue--green range of light when not utilizing a barrier filter. (Editor--— Having used the axiom “if you can see it, you can photograph it” on many occasions, I resent the “old photographer's” label. Seriously, it does hold true, you may have to use filters, specific film and any one or more of various specialized lighting techniques to achieve that promise, but it can be photographed.)
This article was reprinted in “THE PRINT” |