Perfume Fragrance Modification Guide | Note Balance, Projection, Dry-Down

A simple way to modify a perfume is to keep 1 original sample, compare 3 coded samples, smell them at 5 minutes, 30 minutes, 1 hour, 3 hours, and 6 hours, and write down 5 things each time: what it smells like, how strong it is, how far it projects, whether it smells right, and what has changed. Each new version should have 1 main goal and no more than 2 smaller goals. This makes it much easier to find problems in the opening, heart, projection, and dry-down.

A fragrance note is not always one ingredient. A pear, amber, musk, tea, rose, or sandalwood note may be made from several aroma materials. If the pear smells too sweet, the real cause may be the fruit accord, vanilla, amber, musk, or simply the fact that fresh and green notes fade earlier.

Start with what can actually be smelled and when it happens. Do not guess which ingredient needs to change too early.

Use 5 Checkpoints to Find the Problem

These times are useful test points, not fixed industry rules. Some floral, woody, and musky materials can be smelled from the beginning and may still be present hours later.

Fragrance materials also do not always behave the same way when mixed together. A skin study found that materials in a fragrance mixture could affect the way individual ingredients evaporated.^[1]

XUELEI also covers this subject in its guide to how perfume changes on skin and during dry-down.

Fix a Sharp or Weak Opening

A sharp opening does not always mean the citrus needs to be reduced.

For example:

bright citrus → very dry wood

may feel harsher than:

bright citrus → tea or aromatic freshness → light floral → dry wood

The second version may feel smoother even when the citrus level changes very little. Sometimes the problem comes from what follows the note, not the note itself.

A weak opening should be handled in the same way. Adding more citrus may make the first few minutes stronger but leave the rest of the perfume unchanged.

A better structure may be:

bergamot → green tea → light jasmine → clean musk

The bergamot does not need to stay strong for hours. Other notes can keep the perfume feeling fresh after the obvious citrus has faded.

Fix a Weak or Hidden Heart

Use the 30-minute and 1-hour tests to tell these problems apart:

The heart should be easy to describe in plain words. For example:

• soft jasmine with green tea;
• creamy rose with light spice;
• clean lavender with dry woods;
• juicy peach with light white flowers.

If it is hard to say what the perfume should mainly smell like after the opening fades, the heart may not be clear enough.

Fix Sweetness Based on When It Appears

Sweetness may come from fruit accords, vanilla-style notes, gourmand notes, amber, balsamic notes, sweet musks, or creamy woods.

A perfume can smell sweeter later even when the amount of sweet material has not changed. Fresh, green, bitter, and aromatic notes may fade first, making the remaining sweet notes easier to notice.

If the opening already smells right, a useful request would be:

“Keep the current opening. Reduce the vanilla-amber sweetness after two hours while keeping the warmth.”

This is much clearer than simply saying:

“Make it fresher.”

Changing fragrance dosage can also change the balance between notes rather than making every note stronger by the same amount. XUELEI explains this in its guide to perfume sample differences and fragrance dosage.

Fix Floral Problems by Smell Type

An indolic smell is not always a problem. Jasmine, tuberose, orange blossom, and other white-floral styles may use some of this character on purpose. It only needs changing when it becomes stronger than the intended style.

Instead of:

“Reduce the flowers.”

use:

“Jasmine becomes too creamy and heavy after 45 minutes.”

This tells the perfumer what the actual problem is.

Fix Fruit Problems by Smell Type

Useful combinations may include:

• pear + green notes;
• peach + tea;
• fig + dry woods.

A fruit note does not always need to smell completely realistic. A sweet or candy-like fruit style can work well in a playful or gourmand perfume. It only needs changing when it does not match the intended scent.

Separate Projection, Sillage, and Longevity

A perfume may stay on the skin for 6 hours but become hard to smell from a short distance after 1 hour. In that case, longevity is not the main problem. Projection is.

There is no single distance or number of hours that every perfume should reach. A light skin scent, an office perfume, and a richer evening perfume can all have different targets.

Use 2 Evaluators Before Changing Projection

After smelling the same perfume for some time, the wearer may notice it less even though other people can still smell it. This is called olfactory adaptation.^[2]

When projection seems weak, use 2 people:

• Evaluator A: the person wearing the perfume;
• Evaluator B: someone who has not been smelling it continuously.

At the same test time:

• smell the perfume close to the skin;
• check it again from normal conversation distance;
• ask Evaluator B to do the same check.

If the wearer can no longer smell it but Evaluator B still can, the formula may not need changing.

If both people can smell it clearly close to the skin but not farther away, projection has dropped.

If almost nothing can be smelled even close to the skin, longevity may also be weak.

Do Not Use Fragrance Oil as a Simple Strength Dial

More fragrance oil can make a perfume stronger or longer-lasting, but it does not mean projection will increase by the same amount.

At least 4 things affect performance:

• Volatility: how easily a material moves into the air;
• Odor threshold: how little material is needed before it can be smelled;
• Formula balance: how the materials behave together;
• Environment: temperature, airflow, skin, clothing, and spray amount.

A perfume with more long-lasting woods, musk, balsamic notes, or sweet notes may feel richer and stay longer on the skin without projecting much farther.

Research using headspace testing has also found that perfume materials can behave differently when used alone or inside a mixture, and that the product base can affect the way fragrance is released from skin.^[3]

Check 6 Dry-Down Problems

Dry-down is what the whole perfume smells like after the faster-fading notes have become weaker. It is not the same thing as the list of base notes.

The dry-down may still contain parts of the heart, long-lasting base materials, and traces of earlier notes. Their balance changes because they do not all fade at the same speed.

This is why a note pyramid cannot tell exactly what a perfume will smell like after several hours.

Fix Woody and Musky Dry-Down Problems

Common woody problems include:

• pencil-like dryness;
• too much smoke;
• scratchy woods;
• sharp amber-wood notes;
• too much cedar-like dryness.

Instead of saying:

“Remove the woods.”

use:

“Keep the woody base, but reduce the scratchy dryness and keep more softness around the floral notes.”

Musk can also smell very different depending on the style. It may feel:

• clean;
• powdery;
• cotton-like;
• creamy;
• warm;
• skin-like;
• heavy;
• light and airy.

If the dry-down starts to smell like fabric softener, a better request is:

“Reduce the laundry-clean musk effect while keeping a softer skin-like finish.”

Compare 3 Samples Against 1 Original

For example:

• A: original perfume;
• B: less sweetness in the dry-down;
• C: less sweetness while keeping more warmth.

Smell all 3 samples at the same 5 test points.

Always keep the original sample. If every new version is compared only with the version before it, several small changes can slowly move the perfume away from the original target.

XUELEI's perfume sample approval process also checks the opening, development, dry-down, performance, finished product, and production readiness separately.

Record 5 Things at Every Checkpoint

Do not write only:

“3 hours: woody.”

Write:

“3 hours: medium strength; dry cedar is now the main note; jasmine is partly hidden; sweetness is lower; projection is close to the skin.”

This gives enough detail to decide what should change next.

Keep the Test Conditions the Same

• Use simple sample codes such as A01, A02, and A03.
• Use the same type of blotter.
• Do not let wet blotters touch each other.
• Use the same atomizer type when possible.
• Keep the spray method and test area similar.
• Do not change both fragrance dosage and spray amount in the same comparison.

One spray is not an exact dose because different atomizers can release different amounts. The goal is simply to keep obvious testing differences as small as possible.

Test on Blotter and Skin

For fine fragrance, use both:

• Blotter: for easier side-by-side comparison;
• Skin: for real wear testing.

A study comparing glass, a synthetic membrane, perfume test strips, and human skin found measurable differences in the way fragrance evaporated from each surface.^[4]

Skin differences can matter too. A 2025 study found links between fragrance evaporation, the properties of fragrance molecules, and measured skin properties.^[5]

If blotter and skin results are different, check:

• how much perfume was applied;
• where it was applied;
• skin condition;
• temperature;
• airflow;
• other products already on the skin;
• differences in how people smell the perfume.

Do not explain every difference simply as “body chemistry.”

Set 1 Main Target and Up to 2 Smaller Targets

Each revision should have:

• 1 main target;
• 0-2 smaller targets.

For example:

• Main target: reduce sweetness after 2 hours;
• Smaller target: keep jasmine easy to smell;
• Smaller target: keep the current longevity.

Do not change citrus, fruit, jasmine, vanilla, musk, woods, fragrance level, and projection all at once. If the next sample is better or worse, it will be difficult to know which change caused it.

XUELEI's guide to sample differences and fragrance dosage also looks at formula version, dosage, preparation conditions, and other factors separately when comparing samples.

Check What You Lose When You Fix Something

A change is useful only when the improvement is more important than what is lost.

Use a 7-Field Modification Brief

XUELEI's fragrance development process also connects the scent brief with formula work, finished-product testing, safety checks, packaging, and production.

Replace Vague Feedback With Clear Smell Targets

Words such as “premium,” “expensive,” “sophisticated,” and “high-end” may describe brand style, but they do not tell the perfumer what smell needs to change.

Use Each Reference Fragrance for 1-2 Things

A reference fragrance should be used for a clear reason, such as:

• opening brightness;
• floral texture;
• sweetness level;
• projection;
• dry woody character;
• overall weight.

For example:

• “Use this reference only for the brightness of the opening.”
• “Use this reference for the light floral feel.”
• “Use this dry-down direction, but make it less sweet.”

Using too many unrelated references can lead to a perfume with conflicting goals.

Protect 1-2 Signature Features

Before changing the formula, choose 1 or 2 parts that should stay.

A signature feature can be:

• a note combination;
• a contrast;
• a texture;
• the way one stage moves into another;
• a recognizable dry-down.

Examples:

• cold pear + dry tea;
• rose + mineral dryness;
• bright citrus + salty woods.

If every unusual part is softened during each revision, the perfume may become easier to wear but also easier to forget.

Test the Finished Formula Before Approval

Do not approve a perfume only by smelling the fragrance concentrate.

The finished product may also contain alcohol, water, oils, other formula ingredients, and a specific fragrance dosage. The bottle and atomizer can also change how the scent is applied and smelled.

Research has found different fragrance release from skin when perfume materials were used in different product bases.^[3]

The XUELEI perfume manufacturing process includes formula development, dilution, sample testing, stability checks, filtration, filling, packaging, and production control.

Check Physical and Smell Stability Separately

There is no single stability temperature or test length that works for every cosmetic product. ISO/TR 18811:2018 gives guidance for cosmetic stability testing but does not set one fixed group of test conditions, parameters, or pass/fail limits for every product.^[6]

The test plan should match the formula, packaging, expected storage conditions, and sales market.

Check IFRA, Safety, and Market Rules

Changing a fragrance formula or increasing its dosage can also change the amount of restricted fragrance materials or allergens in the finished product.

IFRA Standards can prohibit a fragrance material, limit its use, or set other requirements such as purity specifications. The rule that applies depends on the material and the type of finished product.^[7]

An IFRA Certificate of Conformity shows that the fragrance follows the relevant IFRA Standards for the stated use. It does not replace a full product safety assessment or the laws of the country where the product will be sold.^[8]

For cosmetics sold in the United States, FDA states that fragrance ingredients must meet the same safety requirement as other cosmetic ingredients. FDA also notes that some people may be allergic or sensitive to fragrance ingredients.^[9]

In the European Union, fragrance-allergen labeling requirements under Regulation (EC) No 1223/2009 were updated by Commission Regulation (EU) 2023/1545.^[10]

A home wear test or simple patch test is not proof that a commercial perfume is safe for everyone.

Too Sweet: Use the Time of the Problem

Formula direction: bergamot, pear, jasmine, vanilla, amber, musk.

What happens:

• 0-20 minutes: fresh and balanced;
• 30-60 minutes: fruit starts to smell syrupy;
• 3 hours: vanilla and amber become too strong.

Poor feedback:

“Make it fresher.”

Better feedback:

“Keep the bergamot opening. Reduce syrupy fruit sweetness after 30 minutes. Keep jasmine easier to smell between 30 minutes and 2 hours. Reduce vanilla-amber sweetness in the late dry-down while keeping the current longevity.”

The first 20 minutes already work, so the opening should not be the main area being changed.

Weak Projection: Check Distance and Time Separately

Formula direction: grapefruit, lavender, cedar, musk.

What happens:

• after 1 hour: difficult to smell away from the wearer;
• after 6 hours: still clearly present on the skin.

Better feedback:

“Current longevity is acceptable. Improve projection from about 30 minutes through the first 3 hours. Keep the dry cedar character and do not add more sweetness.”

Use 2 evaluators before changing the formula so that smell adaptation is not mistaken for poor projection.

Generic Dry-Down: Keep the Original Character

Formula direction: fig, green leaves, iris, sandalwood, musk.

What happens:

• opening: clear green fig character;
• after 2 hours: turns into a basic creamy musk;
• later: the perfume is still easy to smell.

Better feedback:

“Keep the green fig character noticeable in the dry-down. Reduce the basic creamy-musk effect. The later stage should stay dry, green, and slightly woody.”

The perfume already lasts. The part that needs work is its character, not its longevity.

Use This 10-Point Approval Check

1. Opening: does the first spray match the intended style?
2. Transition: does the perfume move smoothly into the heart?
3. Heart: is the main scent easy to identify?
4. Balance: does any note take over by mistake?
5. Projection: can the perfume be smelled at the intended distance?
6. Longevity: does it last for the intended wear time?
7. Dry-down: does the later stage still smell good and feel connected to the opening?
8. Signature: are the 1-2 main features still there?
9. Finished product: does the perfume work in the actual formula, bottle, and spray system?
10. Safety: has the finished product been checked for its intended use and sales market?