Fingerprint Brushes | Types an...

A fingerprint powder is required for the latent print development process. Additionally, a fingerprint brush serves as the application medium needed to make fingerprint powder work.

Fingerprint Brush Components

A fingerprint brush is composed of five primary elements:

1. Toe (also known as the head): the end of the hairbrush.
2. Bristles: Brush hair. Fibreglass, polyester, natural animal hairs, feathers, and nylon can all be used to make it.
3. Ferrule: the component that connects the grips to the bristles.
4. Crimp: A ferrule part that compresses the fibres and tightens them to the handle.
5. Handle: It can be curved or flat cylindrical form. Usually composed of acrylic or wood.

Fingerprint Brushes with Fiber Mount Styling

Common types of fibre mount styles:

A. Zephyr Style Brushes

These brushes have straight-cut, very long fibres or hairs that are joined to a slender handle. They typically have equal-sized flat bristles and a large application area. On a handle, a single flat crimp holds the fibres in place.

B. Artist or Mop Style Brushes

Artist-style mounts are another name for mop-style brushes. Shorter hair is placed in the corners of the head (where the brush ends are) and longer hair is placed in the middle. Additionally, the handle is thicker, leveling with the brush's ferrule, which has a thinner handle (other) end.

Types of Fingerprint Brushes For Fingerprint Development

There are seven fingerprint brushes of which four are common:

1. Fiberglass Brush

2. Animal Hair Brush

3. Feather Brush

4. Magna Brush (Magnetic Brush)

5. Polyester Brush

6. Carbon Brush

7. Nylon Brush

1. Fiberglass Fingerprint Brush

Fibreglass brushes have incredibly soft and fine fibreglass bristles and are Zephyr Style Brushes. The diameter of fibres ranges from 7 to 10 mm on average. This type of brush can be considered one of the finest fingerprint brushes. Unlike other conventional brushes, they don't need to be constantly replenished with powder. With over and frequent use, fibreglass brush tips become softer which may become a problem in some cases. 

There are two types of fibreglass fingerprint brushes which includes mildly starched and unstarched. Unstarched fibreglass is more likely to tangle than lightly starched fibreglass. Consequently, less likely to shed glass fibres

According to a study, unstarched fibreglass brushes produce somewhat more accurate fingerprints than starched ones, although they are more difficult to handle and more likely to break.

Disadvantages: Glass fibre brushes tend to break and become airborne which may irritate eyes and skin, and can cause respiratory health problems. One should use specs/masks while using glass fibre, especially using unstarched ones.

2. Animal Hair Fingerprint Brush

Styling options in this type of brush are available in both zephyr and mop styles. The bristle of this type of fingerprint brush is made from animal hair, including camel, squirrel, and pony hair. Body and tip fibre diameters range from 38 to 95 µm and 7 to 27µm respectively.

The surface is scale-covered, making it rougher. They comprise hollow, thin-shelled structures that resemble dumbbells shaped when observed at a cross-section of bristles. They require frequent reloading while producing prints on larger surfaces since they do not effectively retain powder. Zephyr style is longer and the mop style is smaller to medium.

Disadvantages:

• Unsuitable brush for fingerprint powders with an aluminium base.
• Need to be frequently replenished with powder because they do not retain powder well enough.

3. Feather Fingerprint Brush

Soft hair, primarily made of Marabou feathers, is used to make feather brushes. These feathers have tendrils that cover a larger surface area and are easily able to pick up fingerprint powder.

The feather brush requires significantly less pressure than animal hair fingerprint brushes, although it does include jagged barbs spaced regularly that point in the direction of the feather's tip. These jagged barbs resemble the veins found in leaves.

Furthermore, these fingerprint brushes occasionally require pruning to create their tips, which results in rough ends that could harm fingerprints on incredibly flat surfaces. They don't work well with aluminium powder, just like animal brushes don't.

They are typically available in red, white, and black feathers.

4. Magnetic Brush (Magna Brush)

Magna brush is a particular kind of magnetic applicator that is used while applying magnetic powders. They contain magnetic tips that attract magnetic powder into a brush-like structure that can be used to develop latent fingerprints.

They are manufactured commercially in a range of sizes and magnetic strengths. To collect more magnetic powder and create a larger brush, the optimal magnetic brush would have a stronger magnetic field. This has a bigger surface brush area to cover and lowers the likelihood of erasing latent fingermarks.

The simplicity and mess-free use of Magna brush on horizontal surfaces is one of its main benefits. The generated fingerprints can also be cleaned of extra powder by using the Magna brush on the substrate.

Disadvantages:

• Powder tends to fall over vertical surfaces
• Hard to apply over magnetic surfaces

Note: In 1962, MacDonell introduced a magnetic fingerprint applicator which he named ‘Magna Brush’. It has a retractable bar magnetic in a non-magnetic cover design.

5. Polyester Brushes

These come in Zephyr and Artist/mop styles, and their ends are typically tapered. They comprise polyester fibres that are thicker—possibly the thickest—and have 100 μm. fibre diameter. Most of the time, the tips are tapered to a fine point, although some of them have less precise cuts.

The thicker hair makes the brush's overall weight heavier. Due to non-tapered ends and harsher strokes, it might also be responsible for the destruction of latent fingermarks.

Use fibreglass or animal hair fingerprint brushes instead of polyester fingerprint brushes. When it comes to powder performance, polyester fingerprint brushes are similar to artist-styling squirrel hair brushes.

6. Carbon Fingerprint Brush

These brushes are not commonly used. There are very few sellers, and laboratory work is the only application. In the United States, none of the crime scene investigation team members uses carbon brushes. This is most likely due to the fact that they readily shed big clumps of fibre from the brush. Their exteriors are exceedingly smooth.

7.  Nylon Fingerprint Brush 

For general use, it is no longer available on the market. However, you could buy them in the early 2000s. Their cut tips create friction on latent prints and make it easier to capture fingerprints. They perform similarly to feather fingerprint brushes on glass and shiny, polished wood.

Fingerprint Brush Identification Features

Table 1 - Fingerprint Brush and  their Feature

How to Pick the Right Fingerprint Brush for the Surface?

Before obtaining a fingerprint brush, you should first be aware of your typical surfaces to work on. And what kind of fingerprint powder do you intend to use, too. There are at least three different types of fingerprint brushes in every fingerprint development kit. These include a Magna brush, a Marabou Feather Brush, Fibreglass, and Animal Hair Brush (usually camel or squirrel).

In any event, two to three fingerprint brushes are typically needed. A Magna brush is required to use the magnetic powder. Fibreglass brush, on the other hand, performs well with fluorescent and non-magnetic fingerprint powder.

Magna brushes only function with magnetic powders when used in this situation.

Table 2 -  Use of Fingerprint Brush  According to the Surface

Cleaning of Fingerprint Brushes 

Use the Carrying Tube: The majority of fingerprint brushes are packaged in a carrying tube. When not in use, you ought to keep them inside.

Whenever possible, Avoid Washing: For a while, it typically causes fibres to become a little bit rougher and less flexible.

Washing Advice: Be sure to get in touch with the manufacturer first. In most cases, you can rinse with warm water before pressing toward the tips to squeeze out any remaining water. The next day, dry them. Avoid drying fingerprint brushes in the sun. Use a fine-tooth comb to comb

Don't Cut Tips: Don't cut tips unless you have a strategy for re-flaring them. A fine-tooth comb can be used for that.

FAQs

Q. Why would you use a fingerprint brush?

A. Prints cannot be developed with only fingerprint powder. A fingerprint brush fills the necessity for an efficient method of delivery. The strands of a non-damaging fingerprint brush maintain idle friction by holding and not shedding large amounts of powder across surfaces.

Q. What kinds of brushes are used in powder forensics?

A. Forensic professionals typically use one of four different types of fingerprint brushes. These are brushes made of fibreglass, camel hair, and feathers that are used on flat surfaces with non-magnetic or fluorescent powders. Magna brushes with magnetic powder are utilised for surfaces with roughness.

Q. What materials are used to make forensic fingerprint brushes?

A. Glass fibres with a diameter of 7 to 10 µm, animal hair from squirrel, camel, hog, and pony, feather brushes produced from Marabou's bird feathers, and Magna brushes created from a magnetic bar with a demagnetize clip are all used to make forensic fingerprint brushes.

Simple magnetism is used by the Magna brush. The magnetic powder becomes magnetised when a magnet acts on it, as the atoms start to align their electrons with the direction of the magnetic field. The magnetic powder's attraction causes this to take the shape of a "brush" on the Magna brush.

The most popular types of animal hair used to make fingerprint brushes are hog, pony, camel, and squirrel hairs. These brushes are made from hair that is collected from various body parts with a cross-sectional diameter of no more than 95 (or 100) µm.

Q. Which Brush Makes the Best Demonstration in a Classroom?

A. Magna brushes with magnetic particles and animal hair or feather brushes with non-magnetic powders are the most recommended ones as both the development of fingerprints and human health are equally important. The ideal material for development is fibreglass. However, it tends to release flying fibres.

Q. What eliminates extra fingerprint powder?

A. If the prints were made using traditional brushes, the majority of extraneous fingerprint powder can be removed by gently swinging a clean feather brush in the direction of the prints. If you don't have a spare feather brush, you must first clear the used one of any remaining powder before swiping it over the printed area. Simply move clean Magna brush overprints to apply magnetic powder. For magnetic powder, you simply have to move clean Magna brush overprints.