Musks are interesting molecules. Traditionally extracted from various glands of various beasts including the beaver (castoreum) and deer - we now have a vast selection of synthetic musks to choose from. These molecules tend to closely replicate the natural molecule responsible for the desired odour. Amazing scent - cruelty free.
Musks tend to be stable molecules with large carbon rings - I won't get too nerdy here but this essentially means they stick around for longer and make excellent base notes. They also have a wonderful "fixative" nature. This means they make more flighty top notes less volatile - they evaporate less quickly. They can also help to connect the whole scent journey. For example you may choose a musk with a rosey, floral character that is reminiscent of the bright rosey top note of the first spray.
The problem is many of us just can't smell musks. The larger the carbon ring the more difficult it gets. For this reason it is beneficial to add several musks in the mix in the hope that at least one is apparents to the sniffer.
I sometimes like to call this the "Baccarat Rouge effect." Baccarat Rouge 540 is an extremely popular scent by Maison Francis Kurkdijan. Though I have a good idea of several of the ingredients, I can only speculate there is quite a focus on musk molecules; there appears to be a big divide between people who find it extremely powerful and those who claim they can not smell it at all.
I have two favourite musks. One is galaxolide 50 and the other is muscenone. Galaxolide by its nature is a very transparent musk which has most use for its fixative nature - even at higher concentrations it will let other notes shine through though starts to shine in its own right. Muscenone is a very animalic musk which I find extremely difficult to smell neat in the bottle. However when you make a 1% solution in alcohol, that solution smells of muscenone and loses any trace of that alcoholic top note.
In terms of my own creations I noticed this effect for the first time in the #rookscentexperiment "Flaming Dandelion." Though built with a heavy musk base there was a divide between those who could perceive the musks once the top notes had died away and those who felt the scent had disappeared - some of the musks used have enormous longevity and will hang around for days, let alone hours. That being said - this effect was not totally undesirable - more about that in my next blog.
Musks, love them or hate them, are crucial building blocks for a perfume. Manipulating them can be challenging but they are the key to creating a scent as dynamic as a symphony.