Technical Note

Fuming with Cyanoacrylate (Super Glue™)

Introduction

Fumes from cyanoacrylate ester adhesives (Super Glue® and similar products) will develop latent prints. Glue fuming techniques develop latent prints on many surfaces previously considered unsuitable for latent fingerprints. At a demonstration hosted by the Tokyo Metropolitan Police in 1978, forensic scientists of the Criminal Identification Division, Japanese National Police Agency, shared their knowledge of glue fuming with members of the US Army Crime Lab in Japan. Soon criminalists and investigators in a number of countries were conducting experiments and refining the techniques of glue fuming.

Safety

As with all chemicals, always read the MSDS (material safety data sheet) to learn about the safe handling and health hazards of each chemical. The Home Office at New Scotland Yard indicates that fumes from cyanoacrylate ester are irritating but nontoxic at levels encountered in most fingerprint labs. Upon opening the lid of the chamber, arrange for the fumes to be drawn away by a fume hood or vent fan. Remember that this is a super adhesive. Avoid contact with skin, eyes, etc. It is very easy to glue your fingers together, but difficult to get them apart.

Equipment

Fuming Chamber: A container to hold the glue fumes around the piece of evidence is needed. The container can be an aquarium, a large plastic tub, etc. The container should not be too much larger than the items being fumed, and it must be as airtight as possible. The advantage of an aquarium is that the progress of the fuming can be observed. Weather-stripping can be fastened to the top edge of the chamber and a board placed on top to seal in fumes. Covering the inside of the chamber with aluminum foil can make cleanup faster. If the chamber is of see-through material, leave one side uncovered so the fuming can be observed. Space the evidence so that none touches another. Coleman Vacu-Print™: This equipment evacuates the air from the chamber. The evidence is placed inside, a few drops of liquid glue are added and the vacuum pump is switched on. It has been shown that the glue fumes will penetrate folded or crumpled-up plastic baggies of any size when under vacuum. Cyanoacrylate Glue: Loctite® Hard Evidence™ is available in liquid form in one-ounce and one-pound bottles. It is also available in a gel form in convenient-to-use, pull-apart pouches.

Hot plate: This accelerates the processing with the liquid glue.

Processing Instructions

Method One- Pouches: Tape or secure the opened pouch to the lid of the chamber. One pouch is sufficient for a five or ten gallon chamber, but the amount of time of fuming may vary. This method may take from ten to forty minutes, depending on the size of the chamber and the freshness of the pouch. Method Two- Liquid Glue: This method requires the use of heat to accelerate the process. CAUTION: Because it accelerates the process, it is easy to overfume evidence. Place a small hot plate into the chamber. Deposit an amount of glue about the size and volume of a nickel (5˘ piece) onto a small aluminum dish. Place this dish onto the hot plate. Place the pieces of evidence inside the chamber and plug in the hot plate. Secure the lid. This method may reduce the fuming time to ten to fifteen minutes. Observe the evidence every five minutes to check its progress.

Method Three-Vacuum: This method will develop latent fingerprints without leaving excessive residue on the surface of the evidence. Because there is no residue buildup on the evidence, dye-staining for fluorescent examination is more effective. Dyes such as Rhodamine 6G and Ardrox adhere to the glue residue on the item. Items such as garbage bags do not have to be opened up. The fumes will coat all of the surfaces. Place the items of evidence inside the Coleman Vacu-Print™ or other vacuum chamber. If using liquid glue, put a small volume in a small aluminum dish. Or, if using the Hard Evidence™ pouches, cut off a half-inch strip, open it up and attach it to the inside wall of the chamber. Turn on the vacuum pump and evacuate the chamber to approximately 25 inches of Mercury. Turn off the pump and leave the items in the chamber under vacuum for about twenty minutes. If items are left longer there is no danger of overfuming. When ready, allow air back into the chamber, open the lid and remove the evidence. Dye-stain or powder as usual.

Examination

Most latent prints developed with glue fuming will have white ridges and will be quite noticeable. Sometimes, however, the latent prints will be very difficult to see; therefore, each piece of evidence must be carefully inspected. Oblique lighting from a flashlight will be helpful. It is suggested that these prints be photographed before other processes are used. The latent prints can be visually enhanced by dusting with regular or magnetic fingerprint powder contrasting with the background. Once dusted with powder, glue-fumed latent prints can sometimes be lifted with regular lifting tape. The latent prints are quite durable and usually can be lifted more than once. Sometimes the second lift is clearer than the first.

Photography

Visible, contrasting prints can be photographed in the usual way. However, photography of white, glue-developed prints on light-colored or transparent objects may need some different lighting. If the object is transparent, place a piece of paper of contrasting color behind it and photograph as normal. Or, move the light source behind the object. The light will shine through the transparent areas, but the latent prints will appear dark, as no light will shine through. If the object is light-colored and not transparent, it may be necessary to dust or use fluorescent dyes and powders on the latent print to provide the needed contrast.

Helpful Hints

• If you are going to use fluorescent dyes, liquid or powder, underfume the evidence. The liquid dyes, especially, cling to the excessive glue residue and will glow so brightly as to become one shining blur.
• Placing a cup of warm water in the fuming chamber with the evidence could make the glue residue show up whiter and be easier to photograph. It is not necessary to put water in the Coleman Vacu-Print™.
• Refrigeration of the unopened liquid glue bottle or unopened pouches can help to extend the life of the product. Generally, however, the shelf life is about six months to one year.
• Clean the inside of a glass or metal fuming chamber with solvent when the interior appears to be cloudy or chalky. Or if the chamber is lined with aluminum foil, replace it frequently.

Additional Reading

Advances in Fingerprint Technology edited by Dr. Henry Lee and Dr. R. E. Gaensslen
Manual of Fingerprint Development Techniques by the British Home Office, second edition

Ordering Information

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