|B-71000||1||Complete set of chemicals for iodine fumer|
|B-72000||1||Iodine fumer with rubber balloon|
|B-73000||1||Silver plate (for the lifting of prints developed with iodine)|
|B-73100||1||Cleaner for polishing the silver plate|
|B-74500||1||Iodine fixing solution, benzoflavone based|
|C-23000||1||Forceps, 11 cm, rounded|
|C-60000||1||Pair of rubber gloves, thin|
|C-82000||1||Plastic (polystyrene) box, with lid (12x8x3 cm)|
|K-40000||1||Pocket magnifier (3X)|
Latent fingerprints of some days - sometimes weeks - old, can be developed (among other methods) by the BVDA Iodine Fuming Kit. This process is known as the iodine fuming method.
The iodine fuming method may be used on most porous (like paper, cardboard, and unpainted wood) and non-porous surfaces (like hard plastics, porcelain).
The iodine vapour is physically adsorbed by latent fingerprint deposits to give a brown image. There is also some reaction with unsaturated fats, present in those deposits. Because of the corrosivity of iodine, the method is less suitable for non-painted metals, such as aluminium. Due to the brown image that fingerprints develop upon iodine vapour treatment, the method is also not suitable for use on dark surfaces.
Since the iodine adsorbed by objects slowly (measured in minutes) vapourizes again after removing the fumer, prints should be photographed as soon as possible, or fixed. Because of the vaporization of the iodine, the iodine fuming method can be used on objects before other methods (e.g. ninhydrin or indanedione treatment of paper) are tried, without any interference (assuming no fixing is done). The method may, however, interfere with the forensic examination of body fluids.
WARNING: Iodine vapour is toxic and very corrosive. Therefore, care should be taken to minimize inhalation of the vapour.
Instructions for use
The BVDA Iodine Fuming Set consists of the Iodine fumer (B-72000), which should be filled with the chemicals from the set (B-71000), in accordance with the drawing.
The glass wool serves to hold the chemicals in the tube in place. It should therefore be put on both ends.
When the fumer is not in use, the tap should be closed and the dish at the other end replaced by the tight fitting stopper.
On using the iodine fumer, the assembly as shown on the drawing is used. Close the tap first, before inflating the second rubber balloon (with net), with the first balloon. Put the Iodine fumer ON the object (e.g. a piece of paper) and open the tap. The amount of iodine fume can be controlled by obstructing the air stream from the second balloon with the tap.
Do not put the Iodine fumer OVER the object, because in this way the iodine vapour will disappear quickly without aiding development.
When using the iodine fumer, the tube can be held at the height of the iodine crystals. The heat of the hand thus provided will accelerate the vaporization of the iodine.
Benzoflavone iodine fix
As described above, prints developed with iodine will fade, due to the revaporization of the iodine. The prints can be fixed, however, with benzoflavone iodine fix B-74500. The fixing solution can be applied by coating the developed print by a brush or cotton wool, which has been wetted with the fluid. To obtain an equal distribution of the fixing solution, it is strongly recommended to use a sprayer, however (for example a laboratory TLC sprayer).
After treatment with benzoflavone iodine-fix B-74500, the brown colour of the print will have changed to blue/dark blue.
Fingerprints fixed with benzoflavone will be permanent. On non-porous surfaces the prints can be removed by wiping with alcohol.
Silver lifting plate
It is also possible to lift latent prints, developed by the iodine fuming method, with the Silver lifting plate B-73000.
For this purpose, the silver plate should be put on the brown coloured fingerprint and left there for 2 - 3 minutes. The iodine fume will attack the silver plate and the fingerprint will show up (in reverse) as a dark brown or black print. The development is accelerated by sun light.
After photographing or examining the print, the silver plate can be cleaned with silver cleaner B-73100.