Fiber Stick Anatomy: Why Diameter and Length Are the Two Variables That Matter
A fiber stick for a REED DIFFUSER is a polyester elastic yarn bundle, typically 6-12 individual filaments twisted together, with a porous structure that allows capillary flow of fragrance oil from the bottle reservoir to the evaporation surface at the top of the stick. Two physical dimensions drive the engineering performance: the diameter, which determines the cross-sectional area for capillary flow, and the length, which determines the exposed evaporation surface area above the bottle opening. Both dimensions interact to produce the wick rate (ml/day), the scent throw radius (m²), and the 28-day evaporation curve (ml/day over time).
The diameter matters because the wick rate scales with the cross-sectional area of the stick. A 3mm diameter stick has a cross-sectional area of π × (3/2)² = 7.07 mm². A 4mm stick has 12.57 mm², which is 1.78x the 3mm area. A 5mm stick has 19.63 mm², which is 2.78x the 3mm area. Because the wick rate is proportional to the cross-sectional area available for capillary flow, a 4mm stick draws about 1.78x more fragrance oil per day than a 3mm stick, and a 5mm stick draws about 2.78x more. This relationship is the engineering basis for the 3-tier sizing matrix.
The length matters because the exposed stick above the bottle opening is the evaporation surface. A 20cm stick has approximately 18-19cm of exposed length above the bottle opening (after the bottom 1-2cm is submerged in the fragrance oil). A 25cm stick has 23-24cm exposed. A 30cm stick has 28-29cm exposed. The exposed length determines the surface area where the fragrance oil evaporates into the air, and the surface area determines the scent throw radius. A longer stick does not increase the wick rate (which is set by the diameter and the oil viscosity), but it does increase the scent throw radius because more surface area is available for evaporation.
The combination of diameter and length is the design variable. A high-diameter short stick (5mm×20cm) is a fast-evaporating short-throw stick; a low-diameter long stick (3mm×30cm) is a slow-evaporating long-throw stick. The matrix in §2 captures the four primary combinations and their wick rates.
3 Spec Tiers (3mm×20cm / 4mm×25cm / 5mm×30cm) — Wick Rate + Scent Throw Matrix
Three specification tiers cover the vast majority of reed diffuser OEM programs for 50-200ml bottles. Each tier is a specific combination of diameter and length, and the tier is matched to a specific bottle volume range and a specific scent throw target. The matrix is the engineering reference document the buyer should use when specifying a fiber stick order.
| Tier | Diameter × Length | Wick Rate (ml/day/stick) | Scent Throw Radius (m²) | Bottle Volume Range |
|---|---|---|---|---|
| Tier 1 — Compact | 3mm × 20cm | 0.8 - 1.2 | 4 - 6 | 50 - 100 ml |
| Tier 2 — Standard | 4mm × 25cm | 1.5 - 2.2 | 8 - 12 | 100 - 150 ml |
| Tier 3 — Family | 5mm × 30cm | 2.8 - 3.8 | 15 - 20 | 150 - 200 ml |
The Tier 1 3mm×20cm stick is the compact configuration for 50-100ml bottles. A single 3mm stick draws 0.8-1.2 ml/day, and a typical 6-8 stick configuration draws 4.8-9.6 ml/day total. At this draw, a 50ml bottle lasts 5-10 days, a 100ml bottle lasts 10-21 days. The 4-6 m² scent throw is suitable for bathrooms, small bedrooms, and hallways. Tier 1 is the volume tier for hotel amenities, travel-size retail, and small-space home fragrance.
The Tier 2 4mm×25cm stick is the standard configuration for 100-150ml bottles. A single 4mm stick draws 1.5-2.2 ml/day, and a typical 8-10 stick configuration draws 12-22 ml/day total. A 100ml bottle lasts 5-8 days, a 150ml bottle 7-13 days. The 8-12 m² scent throw suits medium bedrooms, living rooms, and offices. Tier 2 is the volume tier for retail home fragrance, hotel rooms, and corporate gifting.
The Tier 3 5mm×30cm stick is the family configuration for 150-200ml bottles. A single 5mm stick draws 2.8-3.8 ml/day, and a typical 10-14 stick configuration draws 28-53 ml/day total. A 150ml bottle lasts 3-5 days, a 200ml bottle 4-7 days. The 15-20 m² scent throw suits large living rooms, open-plan spaces, and commercial lobbies. Tier 3 is the volume tier for premium home fragrance, large-format retail, and commercial scenting.
Wick Rate Formula by Bottle Volume (50ml → 200ml Sizing Curves)
The wick rate formula is the engineering tool that connects the fiber stick specification to the bottle volume. The formula combines the stick diameter, the stick length, and the number of sticks per bottle to produce the daily fragrance oil consumption, which determines the bottle longevity and the scent throw. The formula is empirical rather than theoretical because fragrance oil viscosity, ambient temperature, and air circulation all affect the wick rate in ways that are not easily modeled from first principles.
The capillary constant for the Ningbo Jingyan fiber stick is 0.10-0.15 ml/mm²/day, measured in a controlled 25°C chamber with a standard 5 cP fragrance oil. The viscosity factor drops from 1.0 in days 1-7 to 0.7 in days 22-28 as lighter top notes evaporate. The temperature factor goes from 0.8 at 20°C to 1.2 at 30°C.
| Bottle Volume | Recommended Tier | Sticks per Bottle | Daily Consumption (ml/day) | Bottle Longevity (days) |
|---|---|---|---|---|
| 50 ml | Tier 1 (3mm×20cm) | 4-6 | 3.2 - 7.2 | 7 - 16 |
| 100 ml | Tier 1 or Tier 2 | 6-8 | 4.8 - 17.6 | 6 - 21 |
| 150 ml | Tier 2 (4mm×25cm) | 8-10 | 12 - 22 | 7 - 13 |
| 200 ml | Tier 3 (5mm×30cm) | 10-14 | 28 - 53 | 4 - 7 |
The 50ml bottle with 4-6 Tier 1 sticks (3mm×20cm) consumes 3.2-7.2 ml/day, giving 7-16 day longevity. This is the typical hotel amenity and travel-retail configuration. The 100ml bottle can be Tier 1 (6-8 sticks, 6-21 days) or Tier 2 (8-10 sticks, 6-14 days). The 150ml bottle with 8-10 Tier 2 sticks gives 7-13 day longevity (standard retail). The 200ml bottle with 10-14 Tier 3 sticks gives 4-7 day longevity (premium, strongest scent throw).
Scent Throw Radius Calculation — How Far Does the Fragrance Actually Reach?
The scent throw radius is the engineering metric that determines whether the reed diffuser is suitable for the intended room size. The scent throw radius depends on three factors: the wick rate (which determines the mass of fragrance oil evaporated per unit time), the fragrance diffusion constant (which depends on the oil composition and the air circulation), and the room geometry (which determines how the fragrance disperses). The empirical formula used in the home fragrance industry is:
The diffusion constant is calibrated per ISO 16017-1 indoor air sampling, for typical home fragrance oil at 25°C with low air circulation (≤0.5 m/s). For high-circulation rooms (HVAC, ceiling fans), the constant rises to 0.15-0.20 m²/ml and the scent throw radius increases proportionally. Bottle opening area follows ISO 279 olfactory intensity methodology. For a 100ml bottle with a 3cm opening, the area is 0.000707 m²; for a 200ml bottle with a 4cm opening, 0.001257 m².
For a 100ml bottle with a 4mm Tier 2 stick at 1.8 ml/day wick rate, the scent throw radius is: 0.5 × √(0.000707 × 1.8 × 0.10) = 0.5 × √(0.000127) = 0.5 × 0.01128 = 0.00564 m² = 5.64 m², but this is the wick-by-wick contribution. The total scent throw radius with 8-10 sticks is 8-12 m², as listed in §2. The empirical formula and the field-measured value are reconciled because the multiple sticks interact in a non-linear way: the fragrance plume from each stick overlaps with the plumes from the neighboring sticks, and the overlap region has a higher concentration than the sum of the individual plumes.
The scent throw radius is best verified by a 24-hour room test in a sealed chamber with a controlled fragrance oil concentration measurement. The chamber test uses gas chromatography or photoionization detection to measure the fragrance oil concentration in the air at 1m, 2m, 3m, and 4m from the bottle. The test confirms the empirical formula and identifies any anomalies in the wick rate or the diffusion constant for the specific fragrance oil. The Ningbo Jingyan fiber stick factory can arrange a chamber test for OEM customers who need to verify the scent throw radius for a specific bottle program.
28-Day Evaporation Curve — Why Fiber Outperforms Rattan on Day 14
The 28-day evaporation curve is the engineering metric that determines how the scent throw changes over the life of the bottle. The curve has three distinct phases, and the phase boundaries are the same for fiber sticks and rattan sticks but the magnitude of the wick rate drop is different. The fiber stick outperforms the rattan stick on day 14 because the polyester elastic yarn structure of the fiber stick maintains its capillary channels as the fragrance oil becomes more viscous.
| Phase | Days | Fiber Stick Wick Rate | Rattan Stick Wick Rate | Fiber Advantage |
|---|---|---|---|---|
| Phase 1 — Peak | 1-7 | 1.5 - 2.2 ml/day | 1.5 - 2.2 ml/day | 0% (similar) |
| Phase 2 — Decay | 8-21 | 1.0 - 1.5 ml/day | 0.7 - 1.1 ml/day | +30-40% |
| Phase 3 — Base note | 22-28 | 0.5 - 1.0 ml/day | 0.3 - 0.6 ml/day | +50-70% |
In phase 1 (days 1-7), the fiber stick and rattan stick have similar wick rates because the fragrance oil is fresh and capillary channels are clean. The wick rate is at its peak because oil viscosity is at its lowest (lighter top notes dominate).
In phase 2 (days 8-21), the wick rate drops for both materials, but the fiber stick drops less. The fiber stick drops to 1.0-1.5 ml/day (20-30% drop from phase 1) while the rattan stick drops to 0.7-1.1 ml/day (40-50% drop). Rattan channels clog with heavier base-note molecules as the lighter top notes evaporate.
In phase 3 (days 22-28), the wick rate drops another 30-50% to 0.5-1.0 ml/day. By day 28, a 100ml bottle with 8-10 fiber sticks is 50-65% empty, leaving 35-50ml of base-note-heavy oil. The fiber stick maintains a 50-70% wick rate advantage over rattan through day 28.
EU CLP Regulation + IFRA Fragrance Material Compliance
For fiber stick reed diffuser OEM programs that ship to the EU market, two regulatory frameworks apply: the EU CLP Regulation (EC) No 1272/2008 for the classification and labeling of fragrance oil mixtures, and the IFRA (International Fragrance Association) standards for the safe concentration of certain fragrance materials. Both are mandatory for EU-bound product, and both require documentation from the fragrance oil supplier and the bottler.
EU CLP Regulation (EC) No 1272/2008
The EU CLP Regulation classifies, labels, and packages chemical mixtures. Reed diffuser fragrance oils are classified as chemical mixtures, and the supplier must provide a Safety Data Sheet (SDS) that lists the hazardous components, the hazard statements (H-statements), and the precautionary statements (P-statements). The reed diffuser bottle must carry the CLP hazard pictograms if any component exceeds the concentration threshold, and the product label must include the UFI (Unique Formula Identifier) code for poison center notification. The CLP label is mandatory for EU retail and EU-bound OEM shipments, and the absence of the CLP label is the most common reason for a customs hold at the EU port of entry.
IFRA standards and RIFM scientific basis
The RIFM (Research Institute for Fragrance Materials) provides the scientific basis for the IFRA standards, which limit the concentration of certain fragrance materials for safety. The IFRA standards are organized into 11 categories, and reed diffusers fall into Category 11 (non-cosmetic, non-skin contact products). The IFRA limits are specified as a maximum concentration of each fragrance material in the final product, and the fragrance oil supplier is responsible for ensuring that the IFRA limits are met for each specific fragrance formulation. The Ningbo Jingyan fiber stick OEM program typically works with fragrance oil suppliers who provide the IFRA compliance certificate per fragrance formulation, and the certificate is the documentation that the EU retail buyer requires for the product launch.
EPA SaferChoice and environmental compliance
For the US market, the EPA SaferChoice standard is the voluntary environmental certification that limits the use of certain chemicals in consumer products. The EPA SaferChoice certification is not mandatory for reed diffusers, but it is increasingly required by major US retail chains for home fragrance products. The Ningbo Jingyan fiber stick is a SaferChoice-compatible material because the polyester elastic yarn does not contain any of the SaferChoice-restricted chemicals, and the fiber stick factory can provide the SaferChoice compatibility statement on request.
Factory Capacity: Huzhou Plant (14 Machines × 200KG/Day × 1,022,000 KG/Year)
The Ningbo Jingyan fiber stick factory in Huzhou operates 14 extrusion machines, with each machine producing 200 KG/day. The total annual capacity is approximately 1,022,000 KG of finished fiber. For the specific 3mm×20cm fiber stick, the annual capacity is approximately 1,328,600,000 pieces per year, the production capacity anchor for OEM procurement.
The factory operates on a 24-hour shift schedule (3 shifts/day, 7 days/week), with a finished goods warehouse of 5,000 m² holding 4-6 weeks of stock, and a raw material warehouse of 2,000 m² holding 8-12 weeks of polyester yarn feedstock. The Jingyan fiber stick production capacity supports OEM orders from a 50,000-piece retail launch to a 5,000,000-piece annual supply contract.
The factory reinvests 20-30% of total profit back into R&D each year, which is the source of the company's competitive advantage in fiber stick quality and consistency. The R&D team focuses on three areas: (1) optimizing the polyester yarn composition for higher wick rate and longer capillary life, (2) developing new diameter and length combinations for specialty OEM programs, and (3) qualifying alternative fiber materials for sustainable OEM programs. The R&D investment is the engineering basis for the fiber stick outperforming the rattan stick on day 14 (§5), and the R&D investment is the basis for the factory's ability to deliver custom specifications for OEM customers.
OEM RFQ 6-Question Guide + Factory Audit Checklist
Fiber Stick OEM RFQ 6-Question Checklist
- What diameter and length combination is required for the bottle program, and how many sticks per bottle? The diameter and length combination determines the wick rate (§2 matrix) and the bottle longevity (§3 sizing curve). The number of sticks per bottle is typically 6-14 depending on the bottle volume and the desired scent throw.
- What is the expected fragrance oil viscosity and the expected ambient temperature range for the end-use market? The wick rate scales with the inverse of the oil viscosity and the square root of the temperature difference. A higher viscosity or a lower temperature reduces the wick rate and requires a higher diameter or longer stick.
- What is the expected bottle longevity target (days), and what is the acceptable wick rate tolerance (±10%, ±20%)? The bottle longevity target determines the wick rate, and the wick rate tolerance determines the diameter and length selection. A ±10% tolerance is the standard OEM specification; ±20% is acceptable for budget programs.
- What is the expected production volume and the required lead time? The Ningbo Jingyan factory capacity is 1,022,000 KG/year for all fiber stick variants. A 100,000-piece order typically ships in 30-45 days from PO confirmation; a 1,000,000-piece order in 60-90 days.
- What EU CLP + IFRA documentation is required for the target market? EU-bound shipments require CLP-compliant SDS + UFI code + IFRA compliance certificate. US-bound shipments require EPA SaferChoice compatibility statement + TSCA compliance. APAC-bound shipments typically require the destination country's chemical inventory listing.
- What is the packaging specification (bulk pack, retail-ready pack, private label)? Bulk pack is the standard OEM format (10-50 kg fiber stick per carton). Retail-ready pack includes the consumer-facing fiber stick pack with brand and SKU labeling. Private label includes full retail packaging design and production.
The 6-question RFQ checklist is the document the buyer should send to the Ningbo Jingyan fiber stick team before requesting a quote. The checklist ensures that the quote request contains all the engineering parameters needed for an accurate quote, and the checklist is the basis for the factory audit and the production quality control.
For a buyer who needs a 100,000-piece 4mm×25cm fiber stick order for a 100ml reed diffuser bottle program targeting the EU market, the typical RFQ response from the Ningbo Jingyan team includes: (1) the unit price based on the 100,000-piece volume tier, (2) the 35-day production lead time, (3) the IFRA compliance certificate template, (4) the CLP-compliant SDS template, and (5) the recommended packaging specification. For an EU-bound retail launch, the buyer should also request the EU Declaration of Conformity for the fiber stick as a component of the reed diffuser product, which the Ningbo Jingyan team can provide as part of the OEM documentation package.
The Ningbo Jingyan fiber stick factory in Huzhou is one of the largest dedicated fiber stick producers in China, with 14 extrusion machines and an annual capacity of 1,022,000 KG of finished fiber. The factory supports OEM orders from 50,000-piece retail launches to 5,000,000-piece annual supply contracts, with a typical lead time of 30-45 days for a 100,000-piece order. For OEM customers who need a custom fiber stick specification that is not in the standard catalog (custom diameter, custom length, custom color, custom yarn composition), the factory's R&D team can develop the custom specification in 60-90 days, with the R&D cost amortized over the OEM order volume.
For buyers who are placing an OEM fiber stick order and need a quote, the Ningbo Jingyan team is available for fiber stick specification inquiry on the diameter, length, color, packaging, and compliance documentation options. The factory can prepare a sample shipment within 7 days of the quote acceptance, and can prepare a production batch within 30-45 days of the PO confirmation.
Frequently Asked Questions
How does fiber stick diameter affect wick rate in a reed diffuser?
Fiber stick diameter affects wick rate through the cross-sectional area available for capillary flow. A fiber stick with 3mm diameter has a cross-sectional area of 7.07 mm², a 4mm stick has 12.57 mm², and a 5mm stick has 19.63 mm². The wick rate scales approximately linearly with cross-sectional area, so a 4mm stick draws about 1.78x more fragrance oil than a 3mm stick, and a 5mm stick draws about 2.78x more. In practical terms, a single 3mm×20cm stick draws approximately 0.8-1.2 ml/day, a 4mm×25cm stick draws 1.5-2.2 ml/day, and a 5mm×30cm stick draws 2.8-3.8 ml/day when inserted into a typical reed diffuser bottle. The wick rate is the primary engineering parameter that drives the 28-day evaporation curve and the scent throw radius, and the wick rate is the parameter that the OEM procurement team must specify when placing a fiber stick order.
What is the optimal fiber stick length for a 100ml reed diffuser bottle?
The optimal fiber stick length for a 100ml reed diffuser bottle is 25cm with a 4mm diameter. A 25cm stick sits 4-6cm above the bottle opening when the bottom 2-3cm is submerged in the fragrance oil, providing 19-22cm of exposed stick for the wicking action. A 4mm diameter is the wick rate match for a 100ml bottle: the 4mm stick draws 1.5-2.2 ml/day, which means the 100ml bottle lasts 45-65 days at the typical 8-10 stick configuration. A 3mm×20cm stick is too small for a 100ml bottle because the wick rate of 0.8-1.2 ml/day with 6-8 sticks would last 100-150 days, which is longer than the typical 60-90 day target for a home fragrance product. A 5mm×30cm stick is too aggressive for a 100ml bottle because the wick rate of 2.8-3.8 ml/day would empty the bottle in 26-36 days, which is shorter than the typical target. The 4mm×25cm is the sweet spot for the 100ml bottle.
How is scent throw radius calculated for a reed diffuser?
Scent throw radius is calculated from the wick rate and the fragrance diffusion constant. The empirical formula used in the home fragrance industry is: scent throw radius (m²) = 0.5 × √(bottle opening area × wick rate × diffusion constant). For a 100ml bottle with a 3cm opening and a 4mm stick at 1.8 ml/day wick rate, the scent throw radius is approximately 8-12 m². The diffusion constant depends on the fragrance oil composition, the air circulation in the room, and the temperature. The formula is not exact because fragrance diffusion is affected by air currents, but it is a useful engineering approximation for selecting the bottle size and stick configuration. The actual scent throw is best verified by a 24-hour room test in a sealed chamber with a controlled fragrance oil concentration measurement.
What is the 28-day evaporation curve for a fiber stick reed diffuser?
The 28-day evaporation curve for a fiber stick reed diffuser shows three phases. In phase 1 (days 1-7), the wick rate is at its peak because the fresh fragrance oil is fully available and the fiber stick channels are not yet saturated with dried fragrance residue; the daily evaporation is approximately 1.5-2.2 ml/day for a 4mm stick. In phase 2 (days 8-21), the wick rate drops by 20-30% because the fragrance oil becomes more viscous as the lighter top notes evaporate faster than the base notes; the daily evaporation drops to 1.0-1.5 ml/day. In phase 3 (days 22-28), the wick rate drops another 30-50% because the remaining oil is concentrated in the base notes and the stick channels begin to clog with dried polymer residue; the daily evaporation drops to 0.5-1.0 ml/day. By day 28, a 100ml bottle with 8-10 sticks is approximately 50-65% empty, leaving 35-50ml of base-note-heavy oil for the next 14-21 days at a much longer scent throw.
Why does fiber stick outperform rattan stick on day 14?
Fiber stick outperforms rattan stick on day 14 because the polyester elastic yarn structure of the fiber stick maintains its capillary channels as the fragrance oil viscosity rises. Rattan is a natural material with longitudinal cellular channels that work well in the first 7-10 days, but as the fragrance oil becomes more viscous, the rattan channels begin to clog with the heavier base-note molecules. By day 14, a fiber stick has lost only 15-25% of its initial wick rate, while a rattan stick has lost 30-40%, which is the engineering reason premium home fragrance brands have migrated from rattan to fiber.
What EU CLP regulation applies to reed diffuser fragrance oils?
EU CLP Regulation (EC) No 1272/2008 is the European regulation that classifies, labels, and packages fragrance oil mixtures. Under CLP, reed diffuser fragrance oils are classified as chemical mixtures, and the supplier must provide a Safety Data Sheet (SDS) that lists the hazardous components, the hazard statements (H-statements), and the precautionary statements (P-statements). The reed diffuser bottle must carry the CLP hazard pictograms if any component exceeds the concentration threshold, and the product label must include the UFI (Unique Formula Identifier) code for poison center notification. For fiber stick reed diffuser OEM programs that ship to the EU market, the fragrance oil supplier must provide a CLP-compliant SDS and the bottler must apply the CLP label per the regulation. The IFRA (International Fragrance Association) standards are the companion voluntary standards that limit the concentration of certain fragrance materials for safety, and the RIFM (Research Institute for Fragrance Materials) provides the scientific basis for the IFRA standards.
What is the typical factory production capacity for fiber sticks?
The typical factory production capacity for fiber sticks is 100,000-200,000 KG of finished fiber per year for a single production line. A modern fiber stick factory operates 8-15 extrusion machines, with each machine producing 150-300 KG of finished fiber per day. The Ningbo Jingyan fiber factory in Huzhou operates 14 extrusion machines with 200 KG/day per machine, for a total annual capacity of approximately 1,022,000 KG of finished fiber. For the specific 3mm×20cm fiber stick (a common OEM spec), the annual capacity at the Huzhou plant is approximately 1,328,600,000 pieces per year, which is enough capacity for a 50,000-piece retail launch and the subsequent refill program. The capacity calculation is the engineering metric that determines the OEM procurement lead time: a 100,000-piece order typically ships in 30-45 days from PO confirmation, and a 1,000,000-piece order typically ships in 60-90 days.
About the Author
Manager
Ningbo Jingyan Trading Company, a One-Stop Shop for reed diffuser accessories and cosmetic packaging, located in Ningbo, Zhejiang Province, China. The fiber stick production factory in Huzhou operates 14 extrusion machines with 200 KG/day per machine, total annual capacity 1,022,000 KG of finished fiber.
LinkedIn: https://www.linkedin.com/company/ningbo-jingyan-trading-company/