A comparison between atmospheric/humidity and vacuum cyanoacrylate fuming of latent fingermarks

Abstract

A number of pseudo-operational trials were set up to compare the atmospheric/humidity and vacuum cyanoacrylate fuming processes on plastic carrier bags. The fuming processes were compared using two-step cyanoacrylate fuming with basic yellow 40 (BY40) staining and a one-step fluorescent cyanoacrylate fuming, Lumicyano 4%. Preliminary work using planted fingermarks and split depletions were performed to identify the optimum vacuum fuming conditions. The first pseudo-operational trial compared the different fuming conditions (atmospheric/humidity vs. vacuum) for the two-step process where an additional 50% more marks were detected with the atmospheric/humidity process. None of the marks by the vacuum process could be observed visually; however, a significant number of marks were detected by fluorescence after BY40 staining. The second trial repeated the same work in trial 1 using the one-step cyanoacrylate process, Lumicyano at a concentration of 4%. Trial 2 provided comparable results to trial 1 and all the items were then re-treated with Lumicyano 4% at atmospheric/humidity conditions before dyeing with BY40 to provide the sequences of process A (Lumicyano 4% atmospheric-Lumicyano 4% atmospheric-BY40) and process B (Lumicyano 4% vacuum-Lumicyano 4% atmospheric-BY40). The number of marks (visual and fluorescent) was counted after each treatment with a substantial increase in the number of detected marks in the second and third treatments of the process. The increased detection rate after the double Lumicyano process was unexpected and may have important implications. Trial 3 was performed to investigate whether the amount of cyanoacrylate and/or fuming time had an impact on the results observed in trial 2 whereas trial 4 assessed if the double process using conventional cyanoacrylate, rather than Lumicyano 4%, provided an increased detection rate. Trials 3 and 4 confirmed that doubling the amount of Lumicyano 4% cyanoacrylate and fuming time produced a lower detection rate than the double process with Lumicyano 4%. Furthermore, the double process with conventional cyanoacrylate did not provide any benefit. Scanning electron microscopy was also performed to investigate the morphology of the cyanoacrylate polymer under different conditions. The atmospheric/humidity process appears to be superior to the vacuum process for both the two-step and one-step cyanoacrylate fuming, although the two-step process performed better in comparison to the one-step process under vacuum conditions. Nonetheless, the use of vacuum cyanoacrylate fuming may have certain operational advantages and its use does not adversely affect subsequent cyanoacrylate fuming with atmospheric/humidity conditions.

An assessment of a portable cyanoacrylate fuming system (LumiFume™) for the development of latent fingermarks

“…Two runs were carried out to evaluate Lumicyano™ fluorescence stability (cabinet and LumiFume™) and assessed over a period of days up to a total 28 days. Fluorescence observations were strong after 28 days reflecting previous studies [11,12,14,15]; however, the 10% Lumicyano™ concentration allows for a higher dye concentration providing more time for visualisation before the complete decay of fluorescence (figure 8). Fingermarks developed on glass slides in the cabinet were noted to feature overdeveloped marks (figure 9); however, no overdeveloped marks were observed with the LumiFume™ device which addresses a concern of previous studies that being unable to monitor the mark development (due to the tent) may lead to unintended overdeveloped marks [22].…”

“…This is typically done with powdering or a fluorescent stain such as basic yellow 40 (BY40) and Rhodamine 6G. Over the last decade, investigations and comparisons with one-step fluorescent cyanoacrylates, Lumicyano™, PolyCyano, CN Yellow and PECA Multiband, have taken place [10][11][12][13][14][15][16][17]. One-step cyanoacrylates feature cyanoacrylates with a fluorescent dye or fluorophore conjugated to the glue [18].…”

Detection of Fingermarks—Applicability to Metallic Surfaces: A Literature Review

“…Farrugia performed a comparative study on metallized plastic films, to find out the effect of cyanoacrylate fuming under vacuum. This method is performed in a fuming cabinet.…”

Cyanoacrylate fuming method for detection of latent fingermarks: a review

“…Farrugia et al (2015) suggested the use of atmospheric/humidity fuming process over vacuum fuming process for both two-step and one-step cyanoacrylate fuming for developing latent fingermarks on plastic carrier bags. They also compared two-step cyanoacrylate fuming using basic yellow 40 (LCA4% → LCA4% → BY40) and a one-step fluorescent cyanoacrylate fuming using Lumicyano and observed that two-step process gave better quality prints than one-step process under vacuum conditions.…”