Odor Description by Steffen Arctander

It is part of a perfumer's training and appren-
ticeship to form in his own mind the "unspoken"
terms in which he thinks when he smells and
recognizes a perfume material. But, when com-
municating with fellow perfumers, he must seek
more general expressions in order to be well
understood. The drawbacks of a "basic terms"
system for odor descriptions are equally obvious:
No descriptions are unambiguous or even very
striking. But if we could describe every single of
our perfume materials in such a way that no two
descriptions were alike, and so that every one
fitted like a key to only one material, we could
lean back on a wreath of laurels. We would have
conceived the "impossible": we would have
invented the perfect and foolproof odor classifica-
tion system.
Part of the "romance" or "thrill" in perfumery
work lies in the fact that, not only are all the
materials different in odor but hardly ever will
two perfumers give identical descriptions of the
same material or the same perfume. This coinci-
dence will not occur even if the two perfumers
have been working or have perhaps been educated
in the same perfume laboratory for years. An
odor is not "woody" just because someone else
says so; it will always have a particular print in
your mind. Unfortunately, you are more or less
unable to translate this print verbally to fellow
perfumers, let alone to laymen.
This work does not pretend to be a "codex" for
the perfume industry. The rules and statements
in this book can hardly apply to the conventional
terms used in price lists, etc. For technical reasons,
for lack of space perhaps, the odor descriptions of
perfume materials in price lists are often abrupt
and yet exaggerated. But it certainly is the author's
hope that the present work may serve as an appeal
to the raw material suppliers in the perfume
industry to standardize their labelling and descrip-
tions of perfume and flavor materials. This would
minimize the confusion which has grown tremen-
dously among small and medium-size consumers,
and has even affected the very largest consumers
as well.
The odor descriptions in this work are based
upon studies of the materials during repeated
Blotter-tests. A perfume Blotter, also called a
"smelling-strip", is a piece of pure, odorless,
white, higly absorbent filter paper, about 6 mm.
wide and 12 to 14 cms. long. This strip is marked
clearly with the name or number of the sample of
the perfume material, and is then dipped in the
perfume sample to about 5 mm. or up to 2 cms. on
the opposite end.
The odor from the blotter is studied immediately,
then again after a few minutes, a half hour,
several hours, next morning, etc. until there is no
characteristic odor left. Notes are taken during
all stages of evaporation. Certain materials are
studied in dilution, e.g. oakmoss absolutes, flower
absolutes, civet, etc. The blotter is thoroughly
studied when the perfume oil has "dried" into
the paper. Particularly in oils of high terpene
content, there is a perceptible effect of chromato-
graphic separation of the individual components
of the oil. The "lighter" notes run quickly up the
blotter, while the larger molecules remain at the
end, where it was dipped.
The Topnote ("la note de depart") is studied
repeatedly since it may be of very short duration.
It is the very first perceptible note, the first
impression of odor. The topnote can be very
characteristic of an essential oil and it is also
very often a difficult one to reproduce in the work
on "artificial" essential oils, adulterations, cut-
tings, etc. The true Topnote of an essential oil
can be masked by so-called "still-odors" which
are unwanted notes. Still-notes are usually re-
moved by aeration or ageing of the oil (see also
Aroma-Distillates).
The main and characteristic overall odor of the
oil in the perfume blotter is called the Body-Note.
It has a much longer life on the blotter than has
the topnote, but it is less characteristic of the
odor of the oil, and it is easier to reproduce in
the work on artificial essential oils, etc.
The Dry-Out note is equally as important as
the topnote for evaluation of the oil. The dry-out
will appear after one hour, several hours, or
perhaps not until the next day. It often reveals
adulteration of an essential oil, and it should be
studied repeatedly and carefully.
The Dry-Out notes show the fixative effect of
the components in the oil; it may reveal weakness,
diluents or other foreign additives. Certain oils
do not show a typical dry-out note within the
same day as they are "blottered", e.g. patchouli
oil, vetiver, civet, everlasting, longoza, etc. These
oils can not be justly evaluated within minutes or
hours. It requires at least 24 hours of study and
careful notes. The dry-out note will show the
bodynote, but not the topnote. In exceptional
cases, the topnote is carried along far into the
bodynote and may be perceptible in the dry-out,
e. g. angelica root oil.
The dry-out note tells us about the Tenacity
of the perfume material. The Tenacity, also called
the lasting effect, is a highly appreciated effect
in perfume materials, particularly if the bodynote
and the dry-out note are pleasant fragrances.
Lemon oil has a fresh and pleasant Topnote of
very short duration. It has only a faint and rather
uncharacteristic Bodynote, which may last one
or two hours on a perfume blotter. The Dry-Out
is very faint, uninteresting, yet characteristic, but
of little use to the perfumer. There is no Tenacity
in the odor of lemon oil.
Sage clary oil displays a fresh and delicate
Topnote, which slides gently into a very rich,
sweet-herbaceous Bodynote of long duration.
Its Dry-Out is balsamic-ambra-like, reminiscent
of tobacco and sweet hay, tea-leaves, and with
an unusual Tenacity.
In order to study the behavior of essential oils
on perfume blotters correctly, it is of great
importance that a constant room temperature
and relative humidity be maintained. The author
has personal preference for temperatures lower
than 20° C. in a perfume laboratory, although in
certain countries, a much higher temperature is
quite common (22 to 27°C.). Several ultra-modern
laboratories in Europe are provided with thermo-
stats and humidity regulators to maintain about
17°C. and 45 to 50% relative humidity. The
author has experienced an almost odor-free atmos-
phere in Mid-Sahara, where the temperature was
64° C. on the sand surface, and the relative
humidity was about 0.3%. The author was
unable to smell the peel of an orange which was
squeezed between the fingers under these circumstances
Excessively high humidity is equally unfavor-
able to smelling if the temperature is well above
20° C. It should be noted, however, that during
the study of a dry-out note, the perfumer will
often attempt to produce a "steam-distillation"
by exhaling breath from his nostrils upon the
dry blotter in order to enhance the evaporation
of a weak-smelling material.
The technique of smelling and evaluating per-
fume materials has been thoroughly described in
several works on perfumery practice during the
past decade.