Cyanoacrylate ester, the active ingredient in superglue, is a potent tool for latent print visualization. It works by undergoing anionic polymerization when it interacts with the minute residues of a fingerprint. These residues, primarily composed of amino acids, water, and oils, provide an initiation point for the cyanoacrylate fumes to polymerize, forming a visible white polymer along the ridges of the fingerprint.
Equipment
- Fuming Chamber: A sealed chamber is essential. This could be a purpose-built fuming tank, an aquarium, plastic storage tote, or even a cardboard box in a pinch.
- Humidity Source: A petri dish containing distilled water, small humidifier, or even a damp cloth helps to increase humidity, optimizing polymerization.
- Cyanoacrylate Ester: Commercial superglue or a forensic-grade source.
- Heating Source: Depending on the fuming method, a hot plate, mug warmer, small dish of hot water, or even a hair dryer can be used to volatilize the cyanoacrylate ester.
- Applicator Dish: A small ceramic or glass dish to hold the cyanoacrylate during heating.
- Personal Protective Equipment: Nitrile gloves, safety goggles, lab coat, and appropriate respiratory protection (if ventilation is inadequate)
Important Note: Specific ingredients for cyanoacrylate fuming solutions are often proprietary to forensic supply manufacturers. It's best to procure high-quality solutions from a reputable supplier.
Latent Print Development with Cyanoacrylate Fuming
- Evidence Assessment: Use non-porous or semi-porous items for best results. Examples are glass, plastics, finished wood, metals, and some treated papers.
- Chamber Preparation: Set up your fuming chamber, including the humidity source. Heat source readiness depends on the fuming method you've chosen.
- Evidence Placement: Secure items within the chamber, making sure they won't touch the cyanoacrylate dish during heating.
- Fuming: Add a small amount of cyanoacrylate to the applicator dish. Initiate heating for volatilization. Monitor fuming development closely.
- Fuming Time: This is variable based on chamber size, temperature, and humidity. It could take 15 minutes to several hours. Overfuming can obscure prints.
- Post-Processing:
- Visualization: Developed prints appear as white deposits
- Enhancement: Dyes (Basic Yellow 40, Rhodamine 6G, etc.), powders, or further treatments may be used to enhance contrast depending on the surface.
Storage and Shelf Life of Cyanoacrylate
- Airtight Container: Store cyanoacrylate in the original, tightly sealed container or in a chemically compatible airtight bottle.
- Cool, Dark Place: A refrigerator is ideal for extending shelf life.
- Expiration: Commercial cyanoacrylates may have expiration dates. Homemade solutions have a shorter shelf life. Regularly test with a control item to ensure effectiveness.