Fragrance Basics: Loading, Mixing, and Scent Performance

Fragrance Oils vs. Essential Oils (What Changes in a Candle)

In candles, “scent performance” is mostly about how reliably aromatic molecules stay in the wax, survive the pour and cure, and then release into the air during burning. Two common scent sources behave differently:

Fragrance oils (FO)

• Compatibility: Usually formulated to blend into candle wax and remain stable through heating and cooling. Many are designed specifically for good cold throw (smell when unlit) and hot throw (smell while burning).
• Volatility: Often balanced with a range of note types (top/middle/base) and fixatives so the scent doesn’t disappear quickly.
• Expected throw: Typically more consistent and easier to reproduce across batches, especially for complex scents (bakery, perfumes, “fresh” blends).

Essential oils (EO)

• Compatibility: Natural extracts can be less predictable in wax. Some blend well; others separate, fade, or shift character during heating.
• Volatility: Many EOs are highly volatile (especially citrus and some herbs), meaning they can evaporate or change noticeably if overheated or if added too early.
• Expected throw: Often lighter and more variable. Some EOs perform well (e.g., certain woods/resins), while others smell great in the bottle but become faint in a candle.

Practical takeaway: If your goal is strong, repeatable hot throw, candle-rated fragrance oils are usually the most straightforward. If using essential oils, expect more testing, more subtle throw, and greater sensitivity to heat and timing.

Fragrance Load: Measuring by Weight (Not Drops)

Fragrance should be measured by weight for accuracy and repeatability. “Drops” vary by bottle, viscosity, and temperature, and lead to inconsistent results.

Basic formula

Most makers calculate fragrance as a percentage of the wax weight:

Fragrance (g) = Wax (g) × Fragrance Load (as a decimal)

Example: If you use 500 g of wax and choose a 7% load:

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Fragrance = 500 × 0.07 = 35 g

Typical load ranges (conceptual)

Different waxes and fragrances have different practical limits. Rather than chasing “more is stronger,” aim for a stable, well-bound amount that the wax can hold without sweating, seepage, or poor burn behavior. Many candle recipes fall in a moderate single-digit percentage range, and you should stay within your wax and fragrance supplier guidance.

Why “more” can smell like “less”

• Binding capacity: If the wax can’t hold the fragrance, excess can migrate, evaporate, or interfere with combustion.
• Wick interaction: Too much fragrance can change how the candle burns, which can reduce hot throw even if the candle smells strong unlit.
• Nose fatigue: Very strong blends can quickly desensitize your nose, making the room seem less scented over time.

How Wax Type Affects Perceived Strength (Without Re-teaching Wax Basics)

Even at the same fragrance load, two candles can smell different because waxes release scent differently:

• Some waxes “hold” scent tightly: They may smell softer when unlit but release steadily during a full melt pool.
• Some waxes “broadcast” more readily: They may give a stronger first impression but can be more sensitive to overheating during mixing.
• Crystalline vs. creamy structures: The internal structure of a wax influences how fragrance is trapped and later released, affecting both cold and hot throw.

Practical takeaway: Compare scent performance only when the wax type, load, wick, and cure time are the same. Otherwise, you’re changing multiple variables at once.

When to Add Fragrance and How to Mix (Step-by-Step)

The goal is to add fragrance when the wax is hot enough to incorporate it smoothly, but not so hot that you drive off the most volatile notes.

Step-by-step mixing method

1. Weigh everything first: Place your pouring pitcher on a scale and tare it. Weigh the melted wax. In a separate container, weigh the fragrance amount you calculated.
2. Let wax cool to an appropriate add temperature: Use the wax manufacturer’s recommended fragrance-add range as your primary guide. If you don’t have it, choose a moderate temperature where the wax is fully liquid but not excessively hot.
3. Add fragrance to wax (not wax to fragrance): Pour the pre-weighed fragrance into the wax.
4. Stir deliberately for a timed interval: Stir slowly but continuously, scraping the sides and bottom, for about 2 minutes. This encourages uniform distribution and reduces “pockets” of under-scented wax.
5. Avoid whipping in air: Keep the stir tool below the surface to reduce bubbles, which can affect appearance and sometimes scent perception.
6. Minimize heat exposure after adding fragrance: Once fragrance is in, avoid reheating or holding the wax hot for long periods. Extended high heat can mute top notes and shift the scent profile.

Common mixing mistakes and fixes

Blending Scents: Simple, Repeatable Approach

Blending is easiest when you think in “roles” rather than just names:

• Top notes: Bright, quick-to-smell notes (often more volatile). They give the first impression but can fade faster.
• Middle notes: The main character of the scent. They bridge top and base.
• Base notes: Deep, lingering notes that support hot throw and longevity.

Practical blending method (by weight)

1. Start with two oils only: Keep it simple for your first tests.
2. Choose a ratio: For example, 70/30 or 50/50 by weight (within your total fragrance amount).
3. Pre-blend before adding to wax: Combine the fragrance components in a small cup, stir, and let sit for 5–10 minutes. This helps you smell the blend and reduces last-second changes.
4. Smell on a blotter: Dip a plain paper strip or cotton swab into the blend and smell after 1 minute and again after 10 minutes. If one note dominates, adjust the ratio in the next test.
5. Keep the total fragrance load constant: When testing blends, don’t change the overall load at the same time. Only change the blend ratio.

Blending tips that improve candle performance

• Anchor volatile notes: If a bright note seems to vanish in hot throw, try pairing it with a supportive base note rather than increasing total load.
• Avoid “muddy” blends: Too many strong components can cancel each other out. If the blend smells unclear, remove one component and re-test.
• Test in small batches: Make mini test candles so you can iterate quickly without wasting materials.

Record-Keeping: Your Best Tool for Repeatable Throw

Scent performance is affected by multiple interacting variables. Good notes turn “guessing” into a repeatable process.

What to record (minimum viable log)

• Date and batch ID
• Wax type and amount (g)
• Fragrance type (FO/EO), supplier, and name
• Total fragrance load (%) and fragrance weight (g)
• Blend ratio (if applicable)
• Fragrance add temperature (and pour temperature if you track it)
• Stir time (e.g., 2 minutes)
• Cure time before first test burn
• Test burn notes: cold throw, hot throw, and any scent changes over time

Example log template

Batch ID: S-014A  Date: ____  Wax: ____  Wax wt: ____ g  Wick: ____  Jar: ____(size)  Load: ____%  FO/EO: ____  Fragrance wt: ____ g  Blend: ____/____  Add temp: ____  Stir: 2:00  Cure: ____ days  Cold throw score: ____/5  Hot throw score: ____/5  Notes: ____________________

Evaluating Cold Throw vs. Hot Throw (Test Burn Scoring Rubric)

Cold throw and hot throw are related but not identical. A candle can smell strong unlit and weak when burning (or the reverse). Use a simple, consistent rubric so you can compare batches.

Test setup (keep it consistent)

• Same room size and ventilation: Close windows/doors; avoid strong cooking smells or cleaners.
• Same cure time before testing: Compare like with like.
• Same evaluation points: For example, cold throw at 24 hours after pour and again at your standard cure point; hot throw at set times during a controlled burn.

Cold throw scoring (0–5)

Hot throw scoring (0–5)

During a test burn, evaluate at consistent time points (for example, after the candle has been burning long enough to develop a stable melt pool for that container size). Record both intensity and quality (does it smell like the bottle, or does it shift?).

Quality notes to add alongside the score

• Accuracy: “Smells true to the oil” vs. “turns smoky/perfume-like/flat.”
• Development: Does it change after 30–60 minutes (top notes fade, base notes dominate)?
• Clarity: “Distinct notes” vs. “muddy/blended into one generic smell.”

How to use the rubric: If cold throw is high but hot throw is low, focus on variables that affect release during burning (blend structure, add timing/overheating, and overall formulation choices). If hot throw is good but cold throw is weak, the wax may be holding the fragrance until heat is applied, or the blend may be weighted toward less volatile notes.