A pair of leather gloves, a saddle, a strip of half-burnt birch bark. The leather note in perfume does not come from leather. It is rebuilt from smoke, resin, wood and astringency. This piece takes the leather note apart, then builds a version from plants alone, with black tea, pơ mu and myrrh.
Gloves and saddles
Finished leather smells of its tanning agents and surface finishes, not of the animal. Raw hide has almost no pleasant smell; the leather smell recognised on a new bag is the smell of tannins, oils, smoke and resin that soaked into the fibres during tanning.
In France, the trade in perfumed gloves tied tanning to perfumery for centuries. Leather was scented to cover its own smell, and over time the smell of leather became part of the scent of perfumed gloves. The library page on Grasse records this history.
In the classification of the French perfumers' society SFP, the Leather family carries the code G and is the smallest family, with three subfamilies. The SFP describes it as compositions with dry, sometimes very dry notes that aim to reproduce the characteristic smell of leather: smoke, burnt wood, birch, tobacco. Michael Edwards' system has no separate leather family; leather there is only a facet.
A leather structure has three layers. The top is usually citrus and herbs: bergamot, orange, clary sage, sometimes aldehydes, to lighten a structure that is dark by nature. The heart decides which way the leather leans, towards flowers or towards tobacco. The base is the core: wood tar oils for smoke, styrax and labdanum for warm resin, quinolines for bitterness, with vetiver, patchouli and oakmoss.
Birch tar and cade
Birch bark and wood are heated in a closed vessel, with no water and no steam. The wood does not burst into flame; it is pyrolysed, and what runs out is a dark, viscous liquid with an acrid smoky smell. That is birch tar oil. Together with cade oil, these are the only two essential oils made by this dry distillation.
Russian leather, cuir de Russie, was leather worked with birch bark oil. The oil made it resistant to water and mould and gave it a characteristic smoky smell. According to Nez magazine, Aimé Guerlain had a Cuir de Russie in 1872. Chanel has Ernest Beaux's Cuir de Russie, usually dated 1924; some sources give 1927.
The smoke of birch tar comes from phenols: cresols and guaiacol are the main constituents. Cade oil comes from prickly juniper, Juniperus oxycedrus, also dry distilled, with delta cadinene as its main constituent and a rounder woody smoke.
Dry distillation creates polycyclic aromatic hydrocarbons, PAHs, including benzo[a]pyrene. IFRA therefore prohibits crude birch tar and recommends against crude cade oil; only rectified grades are allowed, and the combined benzo[a]pyrene and 1,2 benzanthracene in the finished product must not exceed 1 ppb. According to the library page, rectified cade oil may still hold benzo[a]pyrene at up to 20 ppb, so it is used only in traces.
Quinolines and synthetic leather
One drop of isobutyl quinoline is enough to make a whole laboratory smell of leather. The molecule is so strong that it is usually sold and used diluted. Its smell is dry, green leather with earthy, rooty facets and a bitter edge.
Isobutyl quinoline is a classic material of twentieth century leather accords. In 1944 Germaine Cellier composed Bandit for Robert Piguet and used this molecule at a very high dose. Bandit is often described as the first leather chypre, and it is also frequently cited within the Leather family; the border between the two groups is not fixed.
On regulation, the library page records that isobutyl quinoline has no dedicated IFRA Standard and is not named individually on the expanded EU allergen list. Quinoline itself, a different molecule, has been prohibited by IFRA since 2010.
The bitterness of isobutyl quinoline has no equivalent among essential oils. The library page on the Leather family notes that vetiver and low-atranol oakmoss only suggest part of it. A leather accord made from plants alone is therefore softer, less bitter, and has to find its dryness elsewhere.
Black tea: astringency and smoke
Black tea leaves that have been fully oxidised and dried carry a smell the fresh leaf lacks: dry, slightly smoky, slightly astringent, close to old leather. In a leather accord that astringency stands in for the tannin of the tanning agents.
Tea as a fragrance material, however, is hard to use. According to the library page, tea leaf extract from Camellia sinensis sensitises skin at very low concentrations, 0.001 percent in guinea pig studies, and IFRA limits it to 0.2 percent on skin in body creams, oils and lotions. Tea can therefore only be a trace in the blend, not its axis.
The dry, woody part has to come from elsewhere. Pơ mu, Fokienia hodginsii, gives a dry, slightly sweet wood, with nerolidol at 30 to 45 percent and fokienol at 20 to 35 percent. Trắc bách diệp, the name Lê Mai uses for cypress oil, Cupressus sempervirens, gives a green, dry, resinous pine smell. These two woods stand where birch stands in a classic leather accord, but without the smoke.
Pơ mu has its own limit too, not on skin but at the source. The library page records Fokienia hodginsii as a rare tree in Vietnam, Laos and southern China, and the oil should come only from suppliers with certified origin. It is distilled from wood and sawdust. The piece on pơ mu tells more about this tree.
Myrrh gives resin: warm, slightly bitter, balsamic, woody. Labdanum, the resin from the leaves of Cistus ladanifer in Spain, gives the warm leather that the library page places in the base of this family. Clary sage, which Lê Mai sells as đơn sâm, makes the top dry and herbal.
The Lê Mai leather blend
Ninety drops, a 30 ml bottle. This blend is set for a larger bottle than usual for one specific reason: tea and cade oil are used at one drop each, and one drop in a 10 ml bottle would already exceed the tea limit.
Pơ mu takes the largest share, close to a third of the blend, as a dry woody base. Cypress and myrrh take a fifth each, one green and resinous, the other warm and bitter. Labdanum adds warm leather. Clary sage and pink pepper hold the top, dry and slightly spicy. One drop of black tea gives astringency, one drop of rectified cade a trail of smoke.
The strength is 15 percent essential oil in perfumer's alcohol: 4.5 ml of oil in 30 ml, about 90 drops. In proportion, each drop is worth about 0.17 percent on skin.
On a blotter, pink pepper and clary sage open first, dry and bright, with the faint smoke of cade just below. After an hour, pơ mu and cypress take over, dry wood with a resinous edge. By evening, what remains is myrrh and labdanum, warm and slightly bitter, close to the inside of an old leather wallet. The astringency of tea is hard to pick out on its own, but it makes the whole blend drier.
| Essential oil | Drops | Share of blend |
|---|---|---|
| Pơ mu (Siam wood) | 27 | 30% |
| Cypress | 18 | 20% |
| Myrrh | 18 | 20% |
| Labdanum | 14 | 16% |
| Clary sage | 8 | 9% |
| Pink pepper | 3 | 3% |
| Black tea | 1 | 1% |
| Cade (rectified) | 1 | 1% |
The limiting oil is tea: the tea leaf page gives an IFRA limit of 0.2 percent on skin. In a 30 ml bottle at 15 percent, one drop of tea gives about 0.17 percent, just below the limit. That is why the blend uses a 30 ml bottle; in 10 ml, one drop would already be 0.5 percent. Do not raise the tea.
Cade is used in its rectified grade only. According to the library, rectified cade may contain benzo[a]pyrene at up to 20 ppb; at 0.17 percent in the product its estimated contribution is about 0.03 ppb, below the IFRA threshold of 1 ppb. A supplier's certificate of analysis is needed to confirm it. Pơ mu sits at about 4.5 percent on skin, cypress and myrrh at about 3 percent, labdanum at about 2.3 percent; the library pages give no specific dermal limit for these four.
Myrrh is strictly contraindicated in pregnancy and breastfeeding, by all routes; this blend is not for those situations. Pink pepper belongs to the same family as cashew and mango and may cause reactions in people allergic to that family; here it is about 0.5 percent. Try it on a small patch of skin before wider use.
Soft leather and smoky leather
Two leather bags set side by side can smell completely different. One is soft suede, close to powder and flowers. The other is thick tanned hide, smelling of smoke and resin. The Leather family in perfume divides along those two directions as well.
The SFP divides the family into three subfamilies: G1 Leather, G2 Floral Leather and G3 Tobacco Leather. Flowers such as orris, jasmine, ylang-ylang, carnation and violet soften the leather, leading to G2. Tobacco, honey, hay and coumarin lead to G3. Saffron adds a dry, slightly metallic leather facet.
The blend above sits close to G1, but without the heavy smoke of birch. To move towards soft leather, take off some cade and add a little flower; to move towards smoky leather, cade is the choice, but only within the PAH limit already calculated. The piece on castoreum tells the animal side of the leather note, the side this blend replaces with labdanum.
Caron's Tabac Blond of 1919, composed by Ernest Daltroff, put leather, tobacco and flowers in one bottle; Nez magazine regards it as the perfume that truly opened the Leather family. Knize Ten, the perfume of the Vienna tailor Knize, appeared in 1924. More than a century later the structure still stands on the same pillars: smoke, resin, wood, and something astringent.
A leather smell that needs no leather.
Only wood, resin, a trail of smoke, and time for them to settle into one another.