Generally speaking, the thing we want these ingredients to be are a product of distillation. When plant matter is distilled it creates two end products—essential oils and a hydrosol/distillate/floral water/aromatic water. The oil floats to the top and is separated off. The remaining water part seems to have many names, but generally speaking, this is what it should be.
Products sold with these names are not always products of distillation, though. It isn’t uncommon to purchase something with one of these names that is actually an essential oil that has been solubilized in water. These faux hydrosols are typically given away by their foam—if you shake one you’ll get some lather. This is because of the inclusion of a solubilizer, which is technically a surfactant. They can also be given away by an SDS (safety data sheet), which can reveal a solubilizer and essential oil as part of the ingredients of the product.
So, how much does it matter? This is somewhat up to you. They both smell nice and will contribute the scent of the plant in question, so in that sense they can be somewhat interchangeable. As a formulator you really should know what you’re working with, so if you think you’re working with a true hydrosol but it’s actually essential oil solubilized in water, then you don’t know exactly what you’re using (if you’re particularly concerned with keeping things natural the solubilizer may not live up to your standards, either). It’s also worth noting that the chemical compounds that end up in a hydrosol can be different from the ones that end up in an essential oil. If you’re getting a faux hydrosol you’re probably paying quite a lot more than you should be for it as well; there is likely less than 1% essential oil in that “hydrosol”, and if that’s what you want to use then you might as well purchase the essential oil and make it yourself.
Something else you should be aware of: are the hydrosols you’re purchasing preserved or not? If not, I’d recommend adding 0.5% liquid germall plus on arrival; I find it takes me ages to use up a bottle of hydrosol, so I like to add a preservative from the get-go to ensure I get full use of the ingredient. If you manufacture huge batches of something and can drain a bottle of hydrosol the first time you open it you can probably skip adding your own preservative.
Posted in: Ingredients