Cyanoacrylate (CA) Fuming
Definition
The development of latent prints on non-porous surfaces by exposing the item to ethyl or methyl cyanoacrylate vapour in a humidity-controlled environment; the monomer polymerises selectively on the moisture and amine groups in print residue to produce a white poly(ethyl cyanoacrylate) cast of the ridge pattern.
- Applies to
- Non-porous surfaces
- Reagent
- Ethyl or methyl cyanoacrylate vapour
- Reacts with
- Moisture and amine groups in print residue
- Result
- White polymer cast of the ridge pattern
- Environment
- Humidity-controlled fuming chamber
Common questions
Why does CA fuming not work well on porous surfaces like paper?+
Porous surfaces absorb the print residue below the surface, so the vapour cannot selectively polymerise around it the way it does on an impermeable surface where the residue sits exposed, which is why paper is instead processed with reagents like ninhydrin or DFO.
What is typically done to a print after CA fuming develops it?+
The developed white ridge detail is often enhanced further with a fluorescent dye stain and examined under alternate light, or photographed directly under oblique lighting, before the item is packaged for comparison.
Related terms
- 1:1 Macro Photography
- Photography at a reproduction ratio of 1:1 (image sensor size equals subject size); the mandatory standard for all latent fingerprint photography before...
- Alternate Light Source (ALS)
- A device emitting light at selected wavelengths (typically 415 to 535 nm) used to detect biological fluids that fluoresce or absorb light...
- Ardrox
- A commercial fluorescent dye mixture (originally for aircraft-skin crack detection) that fluoresces broadly under 365 nm UV illumination; used as a post-CA...
- Barrier Filter
- An optical long-pass filter placed over the camera lens and worn as goggles by the examiner during ALS examination; blocks the excitation...
- Basic Yellow 40 (BY40)
- A fluorescent dye (excitation 450-490 nm, emission ~530 nm) applied immediately after CA fuming with a simple aqueous rinse to remove excess;...
- Ethyl Cyanoacrylate (ECA)
- The active monomer in forensic CA fuming products and most consumer Super Glue formulations; undergoes anionic polymerisation initiated by nucleophiles (water, amines)...
- Inherent Fluorescence
- The luminescent signal from latent print residue itself under ALS illumination, without any development agent; primarily from sebaceous components such as squalene...
- Lumicyano
- A proprietary Foster + Freeman formulation that combines a fluorescent CA monomer with standard CA developer, enabling simultaneous development and fluorescent marking...
- Rhodamine 6G
- A fluorescent dye applied as a post-treatment to cyanoacrylate-developed fingerprints; excited at 530 nm (green), it emits at 565-590 nm (yellow-orange), greatly...