For latent print development, a fingerprint powder is needed. And to make fingerprint powder works an applying medium is required which is provided by a fingerprint brush.
Parts of Fingerprint Brush
There are five main parts of a fingerprint brush. These are:
- Toe: where hairbrush ends, also called head.
- Bristles: Hair of brush. It can be made from fiberglass, polyester, natural animal hairs, feathers, or nylon.
- Ferrule: part that connects bristles with handles.
- Crimp: part of Ferrule that cramps the fibers and secures them to handle.
- Handle: flat cylindrical or curved design. Usually made of wood or acrylic.
Fiber Mount Styling in Fingerprint Brushes
There are two common fiber mount styling: Zephyr or Artist/Mop.
A. Zephyr Style Fingerprint Brushes
In Zephyr style brushes, fibers/hairs are straightly cut, quite long, and attached to a thin handle. They usually have a wide application area with equal-sized flat bristles. The fibers are attached with a single flat crimp on a handle.
B. Artist or Mop Style Fingerprint Brushes
Mop-style brushes are also called artist-style mounts. The head (brush ends) is made to be rounded with shorter hair at the corners while longer hair in the middle. The handle is also thicker which levels with the Ferrule of the brush with a thinner handle (other) end.
[Table] Zephyr Vs Mop Style Fingerprint Brushes
|Feature||Zephyr Brushes||Artist or Mop Brushes|
|Fibers Arrangement||Almost equal||Shorter at corners and longer in middle|
|Brush head (Toe)||Flat||Rounded|
|Crimp||Single wide crimp as flat cylinder||Double or triple crimp|
|Handle||Thin with uniform area||Thicker stick with curved handle design|
Types of Fingerprint Brushes For Finger Marks Development
There are seven fingerprint brushes of which four are common. All these fingerprint brushes are:
- Fiberglass Brush
- Animal Hair Brush
- Feather Brush
- Magna Brush (Magnetic Brush)
- Polyester Brush
- Carbon Brush
- Nylon Brush
1. Fiberglass Fingerprint Brush
- Style: Fiberglass brushes are Zephyr Style Brushes with ultra-fine and soft fiberglass bristles.
- Average Fiber Diameter: 7 to 10µm. These are one of the thinnest fingerprint brush fibers.
- Powder Retain: They do not require constant powder replenishment like other traditional brushes.
- Always soft: Fiberglass brush tips remain soft and get softer with use (this also creates problems).
- Common sizes: 6″, 7.5”, or 8″ fiberglass fingerprint brush.
Fiberglass fingerprint brushes are available as lightly starched or unstarched. Lightly starched fiberglass is less prone to tangling than unstarched ones. Hence, less prone to shed glass fibers.
It is shown by a study that unstarched fiberglass brushes do slightly better in fingerprint development than starched ones but they are more tangled in use and can break more than starched ones (Source).
Disadvantages: Glass fiber brushes tend to break and become airborne which may irritate eyes, skin, and can cause respiratory health problems. One should use specs/masks while using glass fiber, especially using unstarched ones.
Commercially Available Services:
- You can Custom Design your fingerprint brush for your brand/school from Gordon Brush.
- Various Types of Fiberglass are available at Fingerprintpads.com
Note: If you’re planning to buy for the presentation in a closed environment or for a class with teenagers, I highly suggest you go with other brushes such as feather or animal brushes.
2. Animal Hair Fingerprint Brush
- Style: Both zephyr and mop styling
- Animal hair brushes: Camel, squirrel, and pony hairs brush
- Average Fiber Diameter: at tip = 7 to 27µm, and body = 38 to 95µm
- Structure: Surface is covered with scales that make it rougher.
- Cross-Section: They have hollow structures with thin exteriors which appear dumbbell-shaped.
- Powder Performance: When developing prints on larger areas, they do not retain powder well and need to be recharged regularly.
- Powder Usage: granular or magnetic powders.
- Size: Small to medium in mop style and longer in zephyr style.
- Not optimum brushes for aluminum-based fingerprint powders.
- Do not retain powder very well and needs to be regularly recharged.
Commercial Stores: Check Various Types of Animal Hair Fingerprint Brushes at CSIequipment.com.
3. Feather Fingerprint Brush
Feather Brushes are soft hair that is mainly made from Marabou feathers. These feathers have tendrils that can collect fingerprint powder with ease and cover a longer surface area.
With the feather brush, much less pressure is needed than animal hair fingerprint brushes but they do have jagged barbs at regular intervals pointing towards the tip of the feather. These jagged barbs seem to be vein structures on leaves.
Moreover, the tips of these fingerprint brushes sometimes are made by trimming resulting in coarse ends that might cause damage to finger marks on very smooth surfaces. They, like animal brushes, do not work well with aluminum powder.
They are usually available in three color feathers: red, white, and black.
4. Magnetic Brush (Magna Brush)
When using magnetic powders, a special type of magnetic applicator is used called Magna brush. They have magnetic tips that capture magnetic powder and form a “magnetized brush” that can be directly applied over latent fingermarks.
Commercially, they are available in various sizes and magnetic strength. The best magnetic brush would be with higher magnetic strength so that it captures more magnetic powder and forms a larger brush. This reduces the chance of destruction of latent fingermarks and also has a larger surface brush area to cover.
One of the major advantages of using Magna brushes is the ease and mess-free application on horizontal surfaces. Excess powder can also be removed from the substrate by moving the Magna brush over the developed fingerprints.
Major disadvantages of Magna brushes are; (1) powder tends to fall over vertical surfaces, and (2) 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 are available in zephyr and artist/mop style and usually have tapered ends. They have thicker polyester fibers— probably one of the thickest— and have a fiber diameter of 100 μm. The tips are usually tapered to a fine point but some of them have cut not fine.
The overall weight of the brush is heavier due to thicker hair. It may also be the cause of the destruction of latent fingermarks due to non-tapered ends with heavier strokes.
Avoid using polyester fingerprint brushes over fiberglass or animal hair fingerprint brushes. Polyester fingerprint brushes perform similarly to artist-styling squirrel hair brushes in terms of powder performance.
However, if you want a safer alternative to fiberglass and don’t want to use animal products, Zephyr polyester brushes are the way to go. And, at all costs, avoid using mop-style polyester brushes.
Commercially, they are available as Skye I, II, or III, or Tetra Washable.
6. Carbon Fingerprint Brush
They are rare. Very few sellers and their use are limited to laboratory work. None of the crime scene investigators’ team uses carbon brushes in the USA. This is probably because they profoundly shed large clumps of fibers easily from the brush. They have very smooth surfaces.
I highly suggest you not use them for fingerprint development without proper ventilation and a face mask. It can be used for research purposes and is not suitable for fieldwork.
7. Nylon Fingerprint Brush
These are also absolute. No longer available in the market for common use. However, in the early 2000s, you could buy them. They have chopped tips that cause more friction over the latent prints and increase the chase of getting fingerprints.
Performance-wise they are comparable to feather fingerprint brushes over the glass and glossy polished woods.
How to Identify Which Type of Fingerprint Brush You Have?
|S.No.||Fingerprint Brush||Identification Markers/ Features|
|1.||Fiberglass Brush||Zephyr style long smooth bristles attached to a flat cylindrical handle|
|2.||Animal Hair Brush||Rough with uneven thickness and size. Usually available in artist style.|
|3.||Feather Brush||Soft and light with the highest surface area and has microscopic vein structures|
|4.||Magnetic Brush||Magnetic tip with a de-magnetized rod at the other end.|
|5.||Polyester Brush||Thickest, heavier, and tapered ends|
|6.||Carbon Brush*||Tends to break often with smooth fibers.|
|7.||Nylon Brush*||Chopped tips|
How To Choose Fingerprint Brushes Based on Surfaces?
Before buying a fingerprint brush, you should first be aware of your common surfaces to work on. And also which type of fingerprint powder you’re going to use. In any fingerprint development kit, there are at least three types of fingerprint brushes. These are fiberglass, animal fiber (mostly camel or squirrel), a Marabou feather brush, and a Magna brush.
In any case, you mostly require two to three fingerprint brushes. If you want to use the magnetic powder you need a Magna brush (or artist animal hairbrush). Otherwise, for non-magnetic and fluorescent fingerprint powder, fiberglass fiber works well.
In the case of using Magna brushes, they only work with magnetic powders.
|Glass||Fiberglass, Animal, Magna brushes|
|PVC/ Plastic||Fiberglass, Magna, Animal hair brushes|
|Glossy Wood||Fiberglass, Animal, Magna brushes|
|Metal||Fiberglass, animal, and feather brushes|
|Unpolished wood||Magna brush|
|Paper (fresh)||Magna brush and animal hair brushes|
|Texture surface||Magna brush|
|Smooth Leather||Fiberglass, Magna, and feather|
|Textured leather||Magna brush|
|Plastic Bottles||Magna brush and fiberglass|
|Doorknobs||Fiberglass, feather, and animal hair brushes|
|TV Screens||Fiberglass and feather|
|Mirror||Fiberglass and feather|
|Skin||Physical developer method|
|Mobile Screen||Fiberglass, feather, and animal hair brushes|
|Beginners||Magna brush and fiberglass brushes|
How to Clean Fingerprint Brushes? Advice to Follow
- Use Carrying Tube: Most fingerprint brushes come with a carrying tube. You should keep them in it when not in use.
- Avoid washing whenever possible. It generally makes fibers slightly rougher and less flexible for a period of time.
- Washing Advice: First make sure you contact the manufacturer. In the general case, you can rinse in warm water and then squeeze out excess water by pressing toward the tips. Dry them overnight. Don’t sun-dry fingerprint brushes. Comb with a fine-tooth comb
- Don’t Cut Tips: Don’t cut tips unless you have a plan to make their tips flare again. For that, you can use a fine-tooth comb.
Fingerprint powder alone can’t develop prints. An effective delivering medium is needed which is fulfilled by a fingerprint brush. An idle fingerprint brush holds and doesn’t shed excessive powder over surfaces, maintaining idle friction by their fibers that don’t damage latent marks.
There are mainly four types of fingerprint brushes used by forensic experts. These are fiberglass, camel hair, and feather brushes with non-magnetic or fluorescent powders on smooth surfaces. For texture surfaces, Magna brushes with magnetic powder are used.
Forensic fingerprint brushes are made from glass fibers of 7 to 10µm diameter; animal hair of squirrel, camel, hog, and pony; feather brushes from Marabou’s bird feather; and Magna brushes from a magnetic bar with demagnetize clip.
Magna brush uses simple magnetism. When the magnetic powder is influenced by a magnet, its atoms begin to align electrons with the flow of the magnetic field, which makes powders magnetized. This forms a “brush” structure on Magna brush by the attraction of magnetic powder.
Most common animal hair fingerprint brushes are made from squirrels, camel, pony, and hog hairs. The hair used for making these brushes are taken from different parts of the body whose cross-sectional diameter is not more than 95µm (~100µm).
Considering both health and fingerprint development equally important, I prefer to use animal hair or feather brushes with non-magnetic powders, and Magna brushes with magnetic powders. Fiberglass is the best material for development, but it tends to shed airborne fibers.
If prints were developed from conventional brushes, lightly swinging with a clean feather brush removes most of excessive fingerprint powder. If you don’t have an additional feather brush, you first have to declutter powder from the used one and then swipe it overprints. For magnetic powder, you simply have to move clean Magna brush overprints.
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