A hydrosol is the aromatic water left after steam distillation. It is not a diluted essential oil, and it is not a toner with a story.
The plant’s water-soluble fraction lives there: lighter, quieter, often more skin-true than the oil. Helichrysum hydrosol does not smell like helichrysum oil. Rose hydrosol does not replace rose otto. That is the point.
Use it as a mist, a compress, or the water phase in a simple cream. Do not boil it. Keep it cool, and finish an opened bottle in a few months — it is water, and water does not keep like oil.
If you only ever reach for the essential oil, you are missing half of what came off the still.