New research alert!
A new study shows the antibacterial potential of a synergistic formulation of Neroli hydrosol with the essential oils of May chang, Clove bud and Rosewood in acne treatment. The Neroli hydrosol very effective alone, and worked better than Roman Chamomile hydrosol.
This was an in vitro study, so the exact dilutions used are not in fact a guideline to the amounts that will work in a product, which will be greater. There are safety issues for both May Chang and Clove bud in topical use, and an appropriate solution for the essential oils would be 5 drops May Chang, 1 drop Clove bud and 1 drop Rosewood in one ounce of base. This gives about 0.7%, which is safe, and is also 10 times greater than the concentration used in the research.
You could replace Rosewood with Ho wood, the effect should be similar.