How to Choose a Reed Diffuser Base | Evaporation Rate, Scent Throw, Formula Compatibility

Choose the base that passes all four checks: the fragrance stays stable, the liquid moves through the intended reeds, scent remains useful for the target period, and liquid loss is not unnecessarily high. Compare bases with the same fragrance concentration, bottle, reeds, fill weight, room, and test period. A low-viscosity or slow-evaporating raw material is not automatically the better diffuser base.

Compare Base Types

A carrier that performs well with citrus may not give the same result with woods, musks, or balsamic fragrances. XUELEI's fragrance development and manufacturing scope therefore evaluates the fragrance together with the final home-fragrance format.

Check DPG Fit

Dipropylene glycol, or DPG, has low raw-material volatility. The ILO/WHO International Chemical Safety Card lists a vapor pressure of about 4 Pa at 25°C.^[2] IFRA also identifies solvents such as DPG as functional fragrance materials rather than materials that receive an IFRA Certificate of Conformity.^[5]

DPG can also be one part of a blend. Do not copy the same DPG percentage from one fragrance into another and assume equal performance.

Read Raw-Material Data Correctly

Reed flow is also affected by pore structure, surface tension, contact angle, and wetting, not viscosity alone.^[1]

When comparing data sheets, use values measured under similar conditions. Viscosity and vapor pressure change with temperature.

Check Alcohol-Rich Formulas

NIOSH lists pure ethanol with a vapor pressure of 44 mmHg and a flash point of 55°F, about 13°C.^[3] These values describe ethanol, not the final diffuser.

Measure Mass Loss

1. Use the same bottle specification for every sample.
2. Add the same amount of finished formula.
3. Use the same reed type, length, diameter, and count.
4. Complete the same setup procedure.
5. Record Day 0 weight with the bottle + liquid + reeds together.
6. Keep the same assembly throughout the test.
7. Reweigh at fixed intervals.
8. Record temperature, position, and unusual airflow.

Average daily mass loss = total mass lost ÷ test days.

Illustrative test data — not industry targets:

Base A uses liquid about 63% faster than Base B. If the scent only improves from 3/5 to 4/5, Base A should be adjusted before it is selected.

Do not call total weight loss “base evaporation.” The lost mass can include carrier and fragrance materials. Leakage, spills, or liquid on the bottle exterior can also change the result.

Set a Useful Product-Life Target

Track useful scent life, not only the day the bottle becomes empty.

Illustrative test data:

If liquid remains on Day 60 but scent drops below the product target on Day 45, the useful life is about 45 days, not 60 days.

Diagnose Weak Scent

Heavy woods, musks, and balsamic materials can behave differently from citrus and aromatic profiles. If the carrier is working but the perfume still gives poor passive diffusion, the fragrance itself may need adjustment. XUELEI's fragrance formulation and testing process checks performance in the intended finished-product format.

Match the Diffuser to the Room

Illustrative room test — not a room-coverage standard:

Record room size, open doors, air-conditioning, nearby windows, heaters, and strong airflow whenever scent throw is scored.

Set Reed Count

Illustrative reed-count test:

Nine reeds use about 42% more liquid than seven in this example without improving the scent score.

Also keep reed material, diameter, and length fixed while comparing bases. A 20 cm reed and a 25 cm reed do not create the same test condition.

Bottle-neck size also changes reed spacing and exposed liquid area. Use the same bottle during carrier comparison.

Control Reed Flipping

IFRA currently places reed diffusers in Category 10A partly because users can handle soaked reeds or refills.^[4]

Set Fragrance Load

Confirm the permitted range for the exact fragrance first. Then test concentrations within that range.

Illustrative data — 15%, 20%, and 25% are not universal recommended concentrations:

The 25% formula gives no scent improvement over 20% and introduces a stability issue. The 20% formula is the better development candidate in this example.

IFRA quantitative restrictions are applied to restricted fragrance materials in the finished consumer product. An allowed maximum is not a target fragrance concentration.^[5]

Reject Unstable Formulas

For transparent products, inspect at minimum after mixing, 24 hours, 72 hours, one week, and relevant cold/warm exposure.

Check Water Before Adding It

Water solubility of one carrier does not prove that the complete diffuser formula is water-compatible. A water-containing formula may also require separate microbiological or preservation review depending on its composition.

Control Temperature

Illustrative temperature test — not a universal performance standard:

The 30-32°C sample loses about 54% more mass than the 20-22°C sample in this example without improving the scent score beyond 4/5.

Use temperatures that reflect real storage, transport, and customer use. Also check longer-term light exposure for fading, darkening, sediment, or scent change.

Test the Final Packaging

Test the intended bottle, stopper, collar, seal, liner, label, adhesive, coating, and printed decoration.

Illustrative three-unit compatibility test:

A Day 1 check would miss the failures appearing at Days 28 and 42. XUELEI's quality-control process links formula approval with raw-material, packaging, batch, and finished-product checks.

Score Scent the Same Way

Label prototypes A, B, and C. Record strength, room coverage, scent quality, carrier odor, and overall preference.

Do not rely only on someone who has stayed in the test room for hours. Leave and re-enter the room or use evaluators who have not been continuously exposed to reduce smell adaptation.

Repeat Before Deciding

Illustrative repeatability data:

B3 should be checked for fill error, reed variation, bottle position, airflow, leakage, or weighing error before it is included in an average.

Change One Variable at a Time

Select the Best Formula

Illustrative carrier decision:

Verify the Pilot Batch

If the pilot batch behaves differently from the laboratory sample, check every changed material and process condition before changing the carrier.

Check the Raw-Material Grade

• Purity specification
• Water content
• Odor
• Color
• Trace impurities
• SDS
• CoA where appropriate
• Storage conditions
• Shelf life or retest period

A new supplier or new grade should not automatically replace the approved carrier 1:1. Run a comparison test first.

Check Finished-Product Safety

Adding fragrance can change:

• flash point;
• hazard classification;
• environmental classification;
• label requirements.

Terms such as “natural,” “plant-based,” “eco,” “low odor,” or “fragrance grade” do not replace finished-product assessment. A carrier used in fragrance products also does not make reed diffuser liquid suitable for skin contact.

Check IFRA Limits

Under the currently published 51st Amendment Guidance, reed diffusers are classified as IFRA Category 10A.^[4]

• There is no single IFRA percentage for every reed diffuser.
• Limits depend on the materials in the exact fragrance mixture.
• An IFRA Certificate of Conformity is prepared by the company that formulates the fragrance mixture; IFRA itself does not issue individual certificates.^[5]
• Functional materials such as DPG do not receive an IFRA Certificate of Conformity.^[5]
• Quantitative restrictions are calculated in the finished consumer product.^[5]
• Essential oils can contain constituents that are themselves subject to IFRA Standards.^[5]

As of August 2026, consultation on the proposed 52nd Amendment closed on 12 June 2026. IFRA states that formal Notification is expected toward the end of November 2026.^[6]

Check EU Requirements

For EU sales, check the classification of the finished mixture under CLP.

ECHA states that hazardous mixtures within Annex VIII scope require the relevant poison-centre information and a UFI linked to the notified composition.^[7]