What Is a Smelling Strip, and Why Does It Matter?
The cheapest tool on a perfumer's bench is the one that drives the most decisions. The smelling strip (blotter, test strip, mouillette) is the absorbent paper strip on which fragrance is evaluated. It is what you use before buying a fragrance oil, when comparing one mod with the previous one, when checking an incoming lot against the retain sample or when presenting a scent to a customer.
The value of a smelling strip is that it lets you follow a fragrance over time. On skin, a scent changes with warmth, skin type and the person; paper is a neutral, repeatable surface. Two fragrances applied in the same way to the same paper are compared under the same conditions. The whole journey of the scent, from the first minutes of the top notes to the base trail left the next day, can be seen on the strip.
The problem is that a smelling strip used wrongly leads to wrong decisions: an over-dipped strip, mixed-up labels, a tired nose, strips touching each other. This article sets out the rules for using the smelling strip correctly as a tool of professional evaluation.
The Paper Itself: Material, Size and Storage
Not every piece of paper is a smelling strip. Strips made for fragrance evaluation are odourless, highly absorbent and made of pure cellulose; a perfume shop's thin card sample cards or office paper will not do the same job.
| Property | What is right | Why it matters |
|---|---|---|
| Material | Odourless, additive-free, highly absorbent cellulose | The paper's own odour or coating distorts the evaluation |
| Size | About 130–150 mm long, 6–8 mm wide; pointed or rounded tip | A narrow tip limits how much is taken up; a long body leaves room for a label and a grip |
| Thickness | Light and flexible but not limp | Very thin paper saturates at once; very thick paper releases the scent late |
| Storage | In a closed box, away from fragrant materials | Paper absorbs ambient odour; strips left in the open become "contaminated" |
Like everything in the lab that can take up odour, smelling strips absorb the smell of their surroundings. If an open box sits next to the fragrance shelf for a few days, the strips smell faintly even when unused. Keep the box closed, store it away from fragrant areas and do not evaluate from a box you are unsure about.
Where you hold the strip also matters: never touch the scented end with your fingers. Oil and hand cream from your fingers transfer to the paper and add a foreign note to the evaluation.
Correct Application: Step by Step
A smelling strip is reliable only if it is applied in the same way every time. The sequence below makes two separate evaluations comparable with each other.
- Label first
Write the code, dilution and time in pencil on the top end of the strip, the end that will not be scented: "VTV-01-04 10% 10:15". Trying to write after the scent has been applied means handling and contaminating the strip. Ballpoint and felt-tip pens have their own odour; use a pencil.
- Prepare the dilution
Fragrance oils and strong raw materials are evaluated not neat but as a dilution (usually 10% in ethanol). A neat oil overwhelms the nose and hides the detail. Finished perfume is used as it is.
- Dip to a fixed depth
Dip the tip of the strip about 1 cm into the liquid and withdraw it at once. Every strip goes to the same depth; a difference in strength during evaluation must not come from a difference in dipping depth. Apply a spray product not onto the strip but to the tip of the strip as a single spray from 10–15 cm.
- Wipe off the excess and wait a few seconds
Touch the strip lightly against the neck of the bottle to remove the drop. With alcohol-based samples the first few seconds smell only of alcohol; wait 10–20 seconds before smelling.
- Smell from the right distance
Hold the strip 2–3 cm below your nose, waving it gently; do not touch your nose with it. Take short, calm breaths; deep, long sniffs tire the nose quickly.
- Place it in a holder
Put the strip in a clip holder or strip stand with the scented end in the air. Do not lay strips on the bench or let them touch one another: strips in contact carry their odours across to each other.
Evaluation Over Time
The real job of the smelling strip is to follow how a fragrance develops. A single, instant sniff shows only the opening; the character of the scent emerges over hours. Evaluation is done at fixed time points, and at the same points every time.
| Time | What you see | What to look for |
|---|---|---|
| Immediately (after 10–20 s) | Opening: citrus, aldehydes, green and volatile notes | Brightness, sharpness, first impression; is there an alcohol sting? |
| 10–15 minutes | Transition from top to heart | Is there a gap between opening and heart; is the transition smooth? |
| 1 hour | Heart notes: the floral, spicy, fruity body | The true character of the scent; its fit with the brief |
| 4–6 hours | Transition from heart to base | Is the body falling apart; is the base taking over? |
| Next day | Base notes: musk, woods, amber, resin | Longevity and dry-down character; is an unwanted trail left behind? |
At each time point, take notes: intensity (0–5), character (a few words) and any problem. Short notes are enough; what matters is that the same time points recur in every evaluation. Reading the 1-hour notes of a mod series side by side shows which change fixed what.
Strips are not thrown away until the evaluation is finished. Strips to be smelled the next day wait, labelled, in the holder in a closed, odour-free place; leave space between strong and weak strips standing side by side so that they do not affect one another.
Common Mistakes and Frequently Asked Questions
Most wrong decisions made with smelling strips come from a few habits: over-dipping, unlabelled strips, smelling many strips at once and carrying on with a tired nose. The nose tires after roughly 15–20 minutes of intensive evaluation and starts to perceive the same scent as weaker; a short break and fresh air are a more reliable reset than coffee beans. A "this one is weaker" verdict given with a tired nose usually describes the state of the nose, not the strip.
Is a test strip the same as a smelling strip?
Should I smell a fragrance oil neat or diluted?
How far should I dip the strip?
How many strips can I evaluate at the same time?
Why does a perfume that smells good on paper smell different on skin?
Do coffee beans reset the nose?
What should I do with used strips?
What should I watch for when comparing a lot with the retain sample?
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