Speak the Language of Brushes with Confidence
Not sure what “filament set” or “bristle stiffness” really means? You’re not alone. Industrial brush design comes with its own set of terms—and we’re here to make them easier to understand.
Whether you’re reading a spec sheet, placing an order, or just trying to explain a design to your team, this glossary breaks down the lingo so you can move forward with clarity and confidence.
Use the list below to get familiar with common industry terms. And if you ever have a question we haven’t covered, just contact our team—we’re happy to help.
Glossary of Terms
Abrasion resistance measures how well a fiber withstands wear caused by friction or repeated contact with surfaces. High abrasion resistance means longer brush life and more consistent cleaning or finishing performance. Brushes exposed to rough surfaces, sharp edges, or constant rotation benefit from fibers engineered for superior abrasion resistance.
Carolina Brush proudly offers custom brushes featuring top-of-the-line abrasive nylon filaments.Featuring a long wearing abrasive filament impregnated with silicone carbide particles, our line industrial abrasives are ideal for textile machines and conveyors.
Popular Uses for Abrasive Filament Brushes:
- Cleaning
- Polishing
- Paint Stripping
- Deburring
- Finishing
- Wood Aging
Types of Abrasive Brushes:
- Strip
- Wheel
- Tube
- Cylindrical
- Cup
Have a Custom Job? Carolina Brush offers custom made abrasive brushes in a variety of shapes, sizes, and applications.
For applications where synthetic filaments are not optimal, Carolina Brush is pleased to offer a selection of animal hair for use in our industrial brushes. Compared to synthetic brush fiber, natural brush bristle burns less easily, offers less electrostatic charge, is biodegradable, skin friendly and has much better resistance to heat than synthetic options. In addition, natural fibers like goat hair are very soft and fine, with the ability to reach places that synthetic fibers wouldn’t be able to.
Bassine fiber is a superior grade of Palmyra fiber. The fibers are coarse and stiff and range in color from dark brown to black. Good water resistance and its coarseness makes it ideal for stiff scrub brushes.
Bend recovery is a fiber’s ability to return to its original position after being sharply bent. Poor bend recovery is one of the most common causes of brush failure — when fibers stay permanently deformed, the brush loses contact efficiency and overall performance. Materials with excellent bend recovery retain their form and continue to deliver consistent results even under repeated mechanical stress.
Boar hair brushes have been around since the early 1800s and are still one of the most popular animal hair brushes today. Hog hair brushes are naturally stiff and work well with oil and acrylic unlike goat hair brushes. Their stiffness allows you to apply more paint evenly. It is durable and water resistant. Hog hair brushes can also be used to clean cars because of their stiffness.
Available in both straight and crimped forms.
This wire withstands tougher scrubbing. Is used primarily in wire wheels, scratch brushes and rotary floor brushes.
The above compares in a general way some of the properties of the synthetic filaments we most commonly use to aid in distinguishing between them when selecting the filament best suited for a particular application.
Flex fatigue resistance describes how many times a fiber can bend back and forth before it begins to crack or break down. In applications where brushes flex continuously — such as conveyor cleaning, polishing, or sealing — fibers with high flex fatigue resistance are essential to maintain reliability and extend service life.
Flicking action, sometimes called springiness, describes how well a fiber snaps back after being bent or deflected. A fiber with strong flicking action maintains energy and motion, making it ideal for light sweeping, cleaning fine debris, or dusting delicate surfaces. It’s less critical in heavy-duty scrubbing brushes where stiffness and durability take priority over flexibility.
Solvent resistance indicates how well a fiber maintains its mechanical and chemical properties when exposed to oils, fuels, acids, or cleaning agents. A fiber with excellent solvent resistance will retain its stiffness, shape, and color even in harsh chemical environments — ensuring predictable, long-term performance in industrial and manufacturing settings.
Very fine and soft. Used for very short trim brushes.
Imported from Europe and China. Soft to slightly stiff texture. Natural flagging enables brush to reach into cracks to remove fine dust.
Produced in Argentina, Canada, China and the United States. Soft to slightly stiff texture. Used primarily on highly polished areas.
The melting point of a fiber represents the temperature range at which it softens and transitions from a solid to a liquid. Because most brush filaments are thermoplastics, this value isn’t a fixed number — actual melting points can vary by ±20°F depending on the specific formulation. It’s important to note that fibers begin to lose strength and rigidity well before they reach this temperature. The useful working limit of a material is typically much lower than its melting point, which is why temperature ratings matter so much in high-friction or heat-generating applications.
Carolina Brush Company predominantly uses fiber from Type 6, Type 6.6, and Type 6.12. Nylon offers a combination of excellent bend recovery, abrasion resistance, flex fatigue resistance and chemical resistance. It is one of the most versatile synthetic brush fill materials. All nylons absorb water is wet conditions, which will reduce their stiffness; up to 30% for Type 6.12, and up to 80% for Type 6.
Nylon Brush Filament
Nylon has excellent resistance to most substances, including hydrocarbons (such as gasoline, kerosene, and diesel fuel), oils, cleaning solutions, and alkalis. It is however attacked by oxidizing agents, organic and mineral acids, and aromatic alcohols. It will absorb small amounts of water, low molecular weight alcohols (e.g., methyl, ethyl, or isopropyl alcohols) and chlorinated solvents, and be plasticized by them. This may result in a temporary loss of stiffness and tensile strength. Type 6.12 is more resistant to dilute acids and other water soluble substances than Type 6 of 6.6, thereby making it most suitable for wet applications. Some diameters of specialty nylon filament such as abrasive impregnated, conductive 6.6 and heat stabilized 6.6 are available.
Some diameters of specialty nylon filament such as abrasive impregnated, conductive 6.6 and heat stabilized 6.6 are available.
Fiber Property Comparisons
| Filament | Melting Point (*F) | Tensile Modulus (kpsi) | Tensile Strength (kpsi) | Flicking Action | % Bend Recovery | Relative Abrasion Resistance |
| Nylon 6 | 410 | 480 | 53 | Excellent | 97 | Excellent |
| Nylon 6.6 | 495 | 520 | 48 | Excellent | 97 | Excellent |
| Nylon 6.12 | 410 | 480 | 42 | Excellent | 93 | Excellent |
| Polypropylene | 320 | 740 | 53 | Good | 75 | Fair |
| Polyester | 430 | 445 | 31 | Excellent | 92 | Good |
| Filament | Set Resistance | Relative Flex Fatigue Resistance | Water Absorption % Max | Retention of Stiffness in Water | Sunlight & UV Light Resistance | General Solvent Resistance |
| Nylon 6 | Good | Excellent | 9 | Poor | Fair | Excellent |
| Nylon 6.6 | Good | Excellent | 9 | Poor | Fair | Excellent |
| Nylon 6.12 | Good | Excellent | 3 | Good | Fair | Excellent |
| Polypropylene | Fair | Best | <0.1 | Excellent | Poor | Excellent |
| Polyester | Good | Good | 0.5 | Excellent | Fair | Excellent |
The above compares in a general way some of the properties of the synthetic filaments we most commonly use to aid in distinguishing between them when selecting the filament best suited for a particular application.
Alloy composed of mostly copper and brass. Light duty applications that require a soft touch.
Fibers made with polybutylene terephthalate polyester (PBT) can be a good substitute for Nylon in some applications. It has better abrasion resistance than polypropylene, but not quite that of nylon. It has excellent bend recovery, excellent solvent resistance, and excellent oxidation resistance at higher temperatures. It has very good resistance to sunlight.
Polyester Fiber Brushes
The properties of polyester do not change significantly between wet and dry applications because it does not absorb much water, making it ideal for many wet applications. It is however attacked by strong alkalis such as concentrated solutions of sodium hydroxide (lye or caustic soda), calcium hydroxide (lime, mortar), ammonia, trisodium phosphate, or sodium carbonate.
The top quality polypropylene we use is a versatile filament for a wide variety of applications. It has excellent wet stiffness and flex fatigue resistance. It is resistant to most solvents, oils and chemicals and is especially good at resisting strong acids and bases. It may be attacked by oxidizing agents such as hydrogen peroxide, chlorinated solvents (such as 1,1,1-trichloroethane) and aromatic solvents (such as xylene). Polypropylene has good bend recovery, but will take a set more easily than other materials. This issue can usually be addressed with good brush design and reasonable care in handling and packaging.
Set resistance refers to how well a fiber straightens out after being held in a moderately bent position for a long time. Unlike bend recovery, which deals with short-term deflection, set resistance focuses on the effects of sustained stress. A fiber with strong set resistance maintains its shape and alignment over extended use, preventing flattening and uneven wear.
This type wire is the most corrosion resistant wire available in the brush industry
Exposure to sunlight and ultraviolet (UV) light can rapidly degrade certain polymers, causing brittleness, fading, and loss of mechanical strength. When brushes are used outdoors or in UV-rich environments, it’s important to specify materials with built-in UV stabilizers or protective coatings to extend their working life.
Carolina Brush offers a variety of different synthetic brush fiber options for our brushes, including Nylon, Polypropylene and Polyester. Synthetic brush fibers as a whole offer a number of advantages over natural fibers, including higher durability, chemical resistance, and excellent bend recovery. Synthetic fibers also have the advantage of a high absorption rate and high wet stiffness that make synthetic fibers a good choice for wet conditions. In addition, synthetic fibers are also antimicrobial and usually more economical than natural fibers, making them a popular choice. It is because of these particular features that synthetic fiber brushes have found use in applications like wet scrubbing, dentistry, cleaning, artwork, painting and forensics.
A vegetable fiber produced in Mexico from the Mexican Agave plant. The original color is off-white, but it can be dyed any color, but most often dyed black or grey. Tampico is soft to medium with good water retention and acid resistance.
The tensile modulus measures how stiff or flexible a fiber is under tension. A higher tensile modulus indicates a stiffer filament — one that resists stretching or bending. This property affects how the brush performs under load: a high-modulus fiber maintains shape and precision for scraping or polishing, while a lower-modulus fiber offers more flexibility for sweeping, sealing, or contour following.
The tensile strength of a fiber refers to how much pulling force it can withstand before it breaks. In industrial brush applications, tensile strength determines how well a fiber will resist tearing or snapping during operation. When tensile strength drops significantly — due to heat, chemical exposure, or fatigue — it’s often an early sign that the brush is reaching the end of its useful life.
Union fiber is a mixture of two or more materials – usually Tampico and Palmyra. It has a medium stiff texture and is a mix of light and dark brown fibers.
For when animal hair and synthetic fiber aren’t suited to the demands of your job, Carolina Brush offers a selection of quality vegetable fiber brushes. We offer not only the popular Tampico and rugged Bassine fiber, but also the unique Union fiber that offers benefits that come from being made of both Tampico and Palmyra.
Some fiber materials absorb water and become softer or more pliable, while others remain unaffected. Water absorption measures how much moisture a fiber takes on, and retention of stiffness in water indicates how well it maintains its rigidity when wet. In environments with frequent washdowns or humidity, choosing low-absorption materials like nylon 6.12 or polypropylene can help preserve brush performance.
For those that require a strong and sharp filament, Carolina Brush offers a range of wire brush materials for use in our custom made brushes. Perfect for industrial settings, wire is a versatile materials that can be used where a fragile touch is needed as well as offering strength for heavy duty applications like deburring or cleaning. Like other bristle materials, wire has its own set of benefits including rust resistance, the ability to withstand high heat, safe contact with food applications, and high electrical conductivity. It is benefits like these that have led to the use of wire brushes in applications like polishing, finishing, surface cleaning, and the removal of rust, among others. To ensure a brush to fill any kind of job, we offer brushes in Brass, Phosphor Bronze, Carbon Steel and Stainless Steel, each with their own unique features. You ask, we deliver: with nearly a century of experience in producing high quality industrial brushes, you can be sure that we have the experience to handle the most challenging applications and produce brushes that best serve you. Contact us today and we can begin building the appropriate solution to your problems.
