You light a candle, the first fifteen minutes are clear, half an hour later it seems faint, an hour later you can hardly smell anything. So you light a second one. And then a guest walks in and asks why the house smells so strong.
The cause is olfactory adaptation: when you stay in a smell for a long time, the olfactory system reduces its response to that smell to leave room for new information. This is a normal and useful mechanism, because it helps you notice an unfamiliar smell in an environment you already know.
Four familiar situations
- Not being able to smell your own home, though a guest notices it the moment they step in.
- Spraying perfume several more times in a day because you think it has gone, while the person beside you smells it clearly.
- Trying too many scents in a shop and then being unable to tell anything apart.
- Working all day in a workshop full of scent and losing the ability to judge a formula by the afternoon.
How to bring your nose back
The most effective way is to leave the smell. Go outside for five to ten minutes, breathe different air, then come back. For scent testing, limit the number of scents per session and rest between them. For judging a formula, do it first thing in the morning rather than at the end of the day.
At ZUNGZA the convention is that every decision about scent is made in the morning and after the person judging has been outside the workshop for at least ten minutes. This is an internal convention, not a standard method.
One practical piece of advice about candles
If you can no longer smell anything after an hour of burning, do not add a second candle. It is quite possible that the scent level in the room is already enough or more than enough for someone else. The right move is to put the candle out, leave the room for a few minutes, then come back and judge again; or more simply, ask someone who has just come in from outside.
A few questions you often send us
Is olfactory adaptation the same as losing your sense of smell
No. This is a temporary phenomenon and it recovers once you leave the smell. Loss of smell is a different matter and if it lasts you should see a doctor.
Why are some people far more sensitive to scent
Sensitivity differs from person to person and from compound to compound, and it also changes with age, with the state of your nose and with practice. People who work with scent are more sensitive largely because they have learned to pay attention and to name things, not only because their noses are unusual.
Is there a way to clear the nose between two tests
There is no real way to erase it. Breathing clean air is the closest thing. Smelling coffee beans only adds one more strong smell, and many people in the trade do not use that method.