As for the colorants, also the Fragrances used in soap manufacturing can be divided in two types: natural and synthetic.
In handmade soap manufacturing, usually natural fragrances are used; they are alcohol free and they must be formulated for cosmetic products. Another type of fragrances used in cold process are the essential oils.
There is a myriad of oils called "essential oils" obtained by extraction from plants and subsequent distillated. In Soap Making these oils are used as natural perfumes in very low percentage.
The most common essential oils used in soap manufacturing are: Bergamot, Rose, Orange, Citronella, Eucalyptus, Lemon, Lime, Peppermint, Lavender, Chamomile, Sandalwood, Grapefruit, Patchouli, Palmarosa, etc.
In soap industry usually the fragrances are synthetic and also in this case they must be formulated for cosmetic products.
In soap industries the fragrances are added, like the colorants, in the mixing stage of the soap finishing line.
In soap industry fragrances are added from 0,5% (in cheapest soap) up to 3% (in cosmetic soap). A soap with high percentage of fragrances is difficult to work with soap machines, being softer and stickier. There are specialized companies able to create any type of fragrance.