One-Step Cyanoacrylate Development
Written by Mason A. Hines   


In 2007, after being introduced to the science of fingerprints by David E. Weaver, CLPE, I began working with him as the lead research assistant on several successful NIJ-funded research projects. And while the development of “Fuming Orange” occurred after David’s passing in 2010 and after the NIJ funding ended, it would not have come to fruition without his vision and guidance. I will always be grateful that I had the opportunity to work with David, an inspirational teacher and a brilliant inventor, but mostly a treasured friend. —Mason A. Hines

cyanoacrylate development latent prints Fuming Orange Rhodamine 6G
Fuming Orange development is at the bottom and Rhodamine 6G is at the top. This latent was given a score of 4 ("Excellent Value for Comaprison") by all examiners for both processes.

During the initial research period of NIJ grant Award No.: 2009-DN-BX-K196, the goal of developing a cyanoacrylate/dye blend that fluoresced at 532 nm was met with a two-step crystallized product. After the funding was expended, the work was undertaken independently by Executive Forensics and Aneval Inc. in an attempt to produce a simpler, one-step innovation that would function on a hotplate in a fuming chamber or on a portable butane torch for field use. Success was achieved with the development of “Fuming Orange” latent fingerprint developer.

Subsequently, a validation study was conducted with this simpler one-step product. Our optimal goal was to reduce the need for secondary treatment by dye-staining latent fingerprints processed by cyanoacrylate fuming. To that end, we performed a quantitative analysis to compare the methods.

From observations during the refinement phase of creating Fuming Orange, it was projected that the sensitivity of Fuming Orange would approximate or be slightly less sensitive than the traditional method of cyanoacrylate fuming of non-porous items followed by dye staining. A no-cost extension of the original grant was approved to conduct a comparison of the two processes and the results were substantially better than expected.

For example: Latent prints developed with Fuming Orange were consistently equal to or better than latent prints developed with Rhodamine 6G staining.


cyanoacrylate development latent prints Fuming Orange Rhodamine 6G
Fuming Orange development is at the bottom; Rhodamine 6G development is at the top. Among 12 latent print examiners, this sample produced and average score of 3.125 for the Fuming Orange side and an average score of 1.25 for the Rhodamine 6G side.

We performed a comparative analysis of latent fingerprints developed with two methods. One half of a rolled fingerprint was processed with either Fuming Orange or cyanoacrylate fuming, followed by dye staining with Rhodamine 6G. Latent fingerprint examiners were asked to compare side-by-side images of the latent fingerprints processed by these two methods and score them based on the continuity of the ridges and their value for identification.

Two hundred fingerprint impressions were obtained from 25 individuals, volunteers on the campus of Mountain State University, and some local law enforcement officers. No identifying information was gathered from the donors. The samples were placed on 1.5-inch wide strips of consumer grade, heavy-duty Reynolds aluminum foil, marked off into 1.25 x 1.5-inch sections.

Individuals were asked to roll their fingers across the foil in the same manner as taking an inked impression in an attempt to fill the area with the fingerprint deposition. The thumb, index, middle, and ring fingers from each hand were deposited onto the foil. One strip, approximately 6 inches long, held the fingers from the right hand and one strip for the left hand. The strips were then carefully placed into standard paper evidence bags for storage until fuming. Due to the time constraints, 40 samples of the 200 collected were randomly chosen and processed for this study; of those, three pairs showed no development at all from either process and were excluded from the images distributed for examination. The remainder of the samples have been stored for future testing, including a possible study on the relationship between the age of the prints and the quality of the development with both processes.

The fuming tests took place over five consecutive days with eight prints chosen at random from all samples being fumed by each method on each day. This was to allow for the aging of some prints to approximate actual evidence processing conditions.

The first sets processed had been collected 24 hours before fuming and the last sets were aged five days. Immediately before each fuming event, the sample strips were carefully cut in the middle, leaving approximately one-half of an impression on each sample. The strips were secured with clips onto a dowel rod mounted inside a 9.5 x 18-inch, clear, .012-inch thick, polyvinyl chloride disposable fuming chamber (Tritech Forensics item DFC-18). A 2-inch flap had been cut approximately 4 inches from the bottom to serve as an injection port for the fuming device.

A Sirchie Cyanowand (Sirchie item SCW100) was used for all fuming events. The Fuming Orange blend was loaded into a burned-off cartridge designed for use on this torch (Sirchie item SCW200). For the cyanoacrylate fuming, the Sirchie cartridge was used according to the manufacturer’s instructions with a fresh cartridge being utilized for each fuming event. Samples were fumed two strips at a time (eight latent prints) and the order of fuming was reversed with each pair of tests.

The first test was with Fuming Orange. Immediately after removing the samples, the chamber was evacuated and the process was repeated using cyanoacrylate. For the second test, cyanoacrylate fuming occurred first, followed by the Fuming Orange. The left half of all samples was processed with the Fuming Orange; the right side of all samples was processed with cyanoacrylate followed by Rhodamine 6G dye staining. With the events occurring consecutively, the ambient temperature and humidity were equal for each pair of tests.

A mixture of Rhodamine 6G (Sirchie item LV505) was prepared with methanol according to the manufacturer’s instructions and successfully tested before each use for quality assurance. The cyanoacrylate/dye blend was prepared according to the ratios developed during our independent research and introduced to the SCW200 cartridges 24 hours before the first test to allow for complete polymerization on the steel wool. The samples exposed to traditional cyanoacrylate fuming were lightly dipped as prescribed into a tray of Rhodamine 6G and then immediately rinsed with methanol from a nalgene bottle and allowed to dry. The aluminum strips were then aligned with the corresponding strips that were processed with Fuming Orange for photography.

The prints were photographed side by side with a Canon EOS Rebel XSi, 12.2-megapixel, digital SLR camera fitted with a standard orange barrier filter (Sirchie item BMCF100) and a 10x macro lens. A Rofin Polilight Flare Plus with a 505 nm LED head was utilized to illuminate the latents. With the reflective nature of the foil, the light source had to be manually positioned for each photograph to obtain the most accurate image of both halves simultaneously. No computer enhancement was performed on the images. They were, however, resized using Microsoft Office Word 2007 during the insertion into the documents for dissemination to the examiners. This document was converted to a PDF and e-mailed to the 41 latent examiners who had expressed an interest in participating in the study. Later, at the request of one participant, Word documents with the images available for enhancement were transmitted to all examiners.

Volunteers from the latent fingerprint community were recruited through Internet groups, e-mail lists, and from personal contact at the 2011 International Association for Identification (IAI) International Educational Conference. Forty-one examiners responded and were e-mailed the instructions, PDF documents with images, and Excel score sheets. Twelve working and retired latent print examiners with a wide range of experience—from 3.5 years to 30 years; 5 IAI-certified latent examiners, 7 not certified—responded with scores to the first 22 images that were sent, and 10 of those responded to the second set of 15 images for a total of 828 scores, 414 of Fuming Orange and 414 of Rhodamine 6G.

A grading chart of 0-4 (Table 1), developed by Helen Brandey (2004), was provided to the examiners. The examiners were instructed to not judge on placement of the print, because some latents were not centered and, when cut prior to processing, the halves were not evenly distributed.

Table 1
0 No development. No value for comparison.
1 No continuous ridges. All discontinuous or spotty. No value for comparison.
2 One-third of mark continuous ridges. (Rest no development, dotty.) Marginal value for comparison.
3 Two-thirds of mark continuous ridges. (Res no development, dotty.) Good value for comparison.
4 Full development. Whole mark continuous ridges. Excellent value for comparison.


Figure 1

Figure 2

The scores were compiled for analysis and averaging. The results were much better than anticipated. Previous testing warranted the expectation that Fuming Orange would perform at least as well as the Rhodamine 6G processed latents, especially on the freshest prints. But the results from the volunteer examiners showed a significant difference in the average quality of all latent fingerprints examined (Figure 1).

On the 0-4 scale, the 414 scores for latent prints processed using Fuming Orange had a mean score of 3.48; the latents processed with cyanoacrylate and Rhodamine 6G received a mean score of 2.94. The data was inputted into the IBM SPSS predictive analytics software for analysis and a P Value of 1.44E-16 was returned, confirming the significance of the differences between the processes tested.

Although not intended to be a study on the importance of processing evidence when it is “fresh,” the differences in scoring were most discernible in latent prints that were the oldest. There is a significant drop in the scores in all prints developed on days 4 and 5, but the decrease is much greater with those developed with Rhodamine 6G.

There is also the possibility that the fingerprint residue from the samples used in the latter tests came from individuals with less-than-average secretion. However, these results indicate that no matter the cause of the reduced deposition, Fuming Orange has produced significantly improved detail on this portion of the samples. We anticipate continuing this project into a broader study and close attention will be given to this phenomenon.

Rhodamine 6G returned 53 latents that were scored as having no value, whereas Fuming Orange produced only 4 latents scored as “no value”. Sixty marginal latents from the Rhodamine 6G set and 41 from Fuming Orange were reported. The most compelling statistic lies in the difference of identifiable latent fingerprints. Of latents developed with Fuming Orange, 88.9% were deemed identifiable, as opposed to 70.6% processed with the Rhodamine 6G method (Figure 2). In fact, there were only two instances when the Rhodamine 6G produced latents that the examiner’s average score indicated as identifiable while the Fuming Orange print was scored as “no value”. For one of those images, 8 of the 12 examiners felt that the Fuming Orange print was identifiable. For the other image, 2 of the 12 examiners responded with scores indicating that the Fuming Orange latent could be identified.


Based upon the independent scoring of 12 trained latent examiners, the results of this analysis indicate that Fuming Orange should be considered a viable option to the current protocol of employing the secondary treatment of dye staining on non-porous items of evidence. The quality of latent fingerprints produced with Fuming Orange exceeded all expectations and has now been proven to provide better development than dye staining with Rhodamine 6G.

An added benefit of utilizing this new process, in addition to saving time and reducing costs, is that with an appropriate alternate light source, the development of the latent prints can be observed, reducing the risk of overdevelopment. Latent examiners and evidence technicians should experiment with the product and become comfortable with its use before attempting to process actual evidence. They should also consider following up with dye staining until they are confident in the product’s abilities.

This study will soon be expanded and further testing conducted on multiple materials with the results put forth for publication. To date, several varieties of plastics, ceramics, glass, and multiple metals have been processed with Fuming Orange with identical results as in this study. Ceramic tile with fingerprints deposited more than three years ago have been processed with Fuming Orange with positive results. Future analysis will include concentrating specifically on the quality of development on aged latent fingerprints, utilizing the “forced condensation” phenomenon of cooling the evidence immediately prior to fuming. Preliminary experiments have shown a substantial increase in the luminescence of latent prints processed with Fuming Orange when the substrate has been pre-chilled.


Special thanks to the latent examiners who participated in this study: K. Burke, K. Byrne, C. Dordek, J. Drago, J. Godlewski, D. Harness, H. Eldridge, J. Flanders, K. Ford, M. Triplett, P. Warrick, R. Koteles; to Andrew Wheeler, Doctors Jungyun and Gill for their assistance with analyzing the data; to the students of Mountain State University; to the law enforcement officers of Fayette County for donating the fingerprints; and to Charles Steele from Aneval Inc. for his guidance and support.


Bandey, H.L., “The Powders Process, Study ,”. Fingerprint Development and Imaging Newsletter. Sandridge: Police Scientific Development Branch, Home Office. 2004: Report No. 54 ⁄ 04.

Bond, J.W., “Visualization of Latent Fingerprint Corrosion of Metallic Surfaces,” Journal of Forensic Sciences. 2008: 53(4), 812-822.

About the Author

This e-mail address is being protected from spam bots, you need JavaScript enabled to view it was mentored by and conducted latent print development research with the late David E. Weaver, CLPE. He is currently the director of the Fayette County Evidence Center, Mount Hope, West Virginia, and a crime scene investigator for the Oak Hill (West Virginia) Police Department.

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