Impossible to distill, the leather note is actually a combination of ingredients by a perfumer: the simplest, earliest leather accords were a mixture of rectified (boiled) birch tar, castoreum (from the beaver, which eats bark from the birch) and isobutyl quinoline. Modern perfumes mainly use synthesised ingredients, such as suederol, to achieve their effect.
One of the original perfumery traditions were originally also 'Gantiers', or 'glovemakers'. They would scent their gloves using powerful and luxurious odours as a way of covering up the offensive smell of chemicals used in tanning. Traditionally, iris root and labdanum would be used, which is potentially why these ingredients have a leather facet to us.
How does it smell?
Leather can smell rich, luxuriant, tar-like, smoky, warm, dry, sweet, powdery, animalic. It can range from the patent exterior of a military boot to the soft delicacy of the interior of expensive handbags.
Why is it used in a perfume?
Leather exudes elegance and luxury. In a perfume, the addition of a leather note adds dryness, but also a sensual quality, reflecting the somewhat animalic nature of its origins. Also, and most importantly, leather not only smells fantastic as an inspirational material, but is loaded with memories for us: new (or old) leather bags can fill us with nostalgia.
At Penhaligon's, we've used leather in a number of our fragrances, but most importantly is the beautiful leather-suede note at the base of Iris Prima. Taking inspiration from the sole of the ballet slipper, Alberto Morillas decorated the leather note with a delicate floralcy and powder. Endymion, Juniper Sling, and Sartorial also feature Leather in their notes listings.