What Does Metallic Mean?
Metallic means “like metal.” It describes a scent that “recalls metal or stainless steel, with a coldness that seems to pierce the nasal passages and a sensation like a sharp needle.”
This is the so-called smell of metal, but anyone familiar with chemistry may wonder about it. After all, we are supposed to perceive a smell when a compound volatilizes. Do metals, whose melting points (the temperatures at which they become liquid) are extremely high, really volatilize in everyday life? Or are we detecting the smell of something else? (Incidentally, copper melts at 1084°C and iron at 1536°C.)
When do we feel that we can smell iron? When we touch a horizontal bar, a 10-yen coin, a slightly rusty iron tool, and so on. Wait a moment… aren’t these all things our hands have touched?
In fact, there are researchers who asked, “Are we really smelling iron?” and carried out experiments to find out. They were Dr. Glindemann’s team (the paper is freely available, so if you are interested, please follow the link in the references).
They asked participants to smell “a solution mixing iron ions and artificial sweat” and “a solution containing only iron ions,” and describe their impressions. The former smelled like the palm of a hand after touching iron, while the latter had no smell at all. They then used experiments to clarify this relationship between skin and the smell of iron.
Sweaty skin corrodes metallic iron, forming highly reactive Fe2+ ions. Within seconds, the Fe2+ ions are oxidized to Fe3+ ions while simultaneously reducing and breaking down lipid peroxides already present in the skin (note: sebum), forming carbonyl hydrocarbons perceived as a metallic odor. The speed of this reaction creates the sensory illusion that what we smell immediately after touching it is “the metal itself.”
“The Two Odors of Iron when Touched or Pickled: (Skin) Carbonyl Compounds and Organophosphines” (2006, Glindemann)
Interestingly, blood was found to have a metallic odor on its own. This shared metallic odor came from aldehydes and ketones called 1-octen-3-one. Incidentally, these are also present in mushroom, animal, and fish odors.
Thinking back, perhaps you have not noticed much of a smell from brand-new metal? In other words, metallic odor is a smell born from the coming together of skin and metal, and it is also the scent of blood.
Fragrance Materials Used
Representative materials that perfumers use for metallic notes are rose oxide (one of the aroma compounds present in the scent of roses), geranium, lavender, synthetic iris (in Japanese), and aldehydes (in Japanese). Fragrance companies also make other synthetic materials that give a metallic impression. Generally, synthetic materials such as rose oxide and aldehydes are often used.
Perfumes That Illustrate a Metallic Impression
Partly because of their extensive use of synthetic materials, I think AETHER perfumes may make the metallic impression easy to understand. Metallic is a distinctive scent character, so there are not very many examples, but here are a few perfumes with a metallic impression.
・CARBONEUM (Aether, 2016, Amélie Bourgeois & Anne-Sophie Behaghel)
・Rose Alcane (Aether, 2016, Amélie Bourgeois & Anne-Sophie Behaghel)
・ULTRAE (Aether, 2016, Beverley Bayne)
・Concrete (Comme des Garçons, 2017)
・Comme des Garçons 3 (Comme des Garçons, 2002, Mark Buxton)
・Métallique (Tom Ford, 2019, Antoine Maisondieu)
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