Musks in perfumery are like the base notes below the base notes, amplifying everything above them. Musk molecules are large, which means they’re slower to evaporate, adding staying power and “oomph” to any blend they’re in.
Originally, perfumer’s musk came from the musk deer and other animals including civet cats and beavers (castoreum). Today, true animal musks are no longer used, and have been replaced with synthetic musks. The only plant musk is made from the seeds of the ambrette flower, also known as musk mallow.
So what exactly does musk smell like? The answer is a tangled web of scent culture. Animal musks and their synthetic reconstitutions are often overpowering and unpleasant—think manure—unless they’re highly diluted. Dosed properly, they add magic to a blend. Musks can be plush, warm, powdery, creamy, grubby, funky, dirty, indolic, weighty, luxurious, musty, round, or soft.
Musks can also smell clean like laundry—primarily because they are the scent of clean laundry. The large molecules’ staying power makes them perfect for detergents and fabric softeners, which have to retain their scent through the laundry cycle. It’s a scent culture feedback loop: fragrance houses created new synthetic molecules and used them for laundry products, so now we associate their scent with cleanliness and warm, fresh laundry. (Some musk molecules do not degrade in water, causing harmful bioaccumulation, and are increasingly regulated / decreasingly used as a result.)
Some musks smell a little bit wet; some smell a little metallic. Some of them don’t have a smell at all—because the molecules are so large and heavy, about 50% of people are anosmic to (can’t smell) any given musk molecule. For this reason, most perfumes or scent applications will use a handful of different musk molecules, knowing that each person will only smell about half of the musks.