Scenting your handmade soaps is a matter of personal preference. If you are are making soaps for your own use, then you can decide to use either fragrance oils or essential oils based on what you like. If you are selling your soaps, consider your market.
Essential oils are all natural plant essences. They can be derived from the plant material by several methods such as: steam distillation, CO2 extraction or cold pressing.
Steam distillation is done with a still. Pressurized steam is forced through the plant matter. The steam then passes through to a cooling chamber, where the steam is converted back to water. The essential oils from the plant are then skimmed off the surface of the water.
CO2 extraction is where liquid carbon dioxide is used to extract the oils. It is similar to the steam distillation in that pressure is used to extract the oils. When the carbon dioxide is allowed to return to its gas state, the essential oil is separated out and collected.
Cold pressed is the process by which the plant material is physically pressed until the essential oil is extracted. Citrus essential oils are commonly processed this way, as the peels are full of essential oils.
There are some scents where there is no essential oil available (such as banana) or the essential oil is much too costly or environmentally irresponsible to use (such as sandalwood or rosewood). This is where fragrance oils come in. Fragrance oils are a mixture of aroma chemicals. The mix can either be part artificial and part synthetic, or all synthetic. It just depends on the type of fragrance oil. Fragrance oils are not perfume oils, they are aroma chemicals which are not diluted, and like essential oils, should not be placed directly on the skin. They need to be diluted into your final product.
Fragrance oils are usually very complex, and can contain hundreds of aroma chemicals. When using fragrance oils for your soap, make sure that you are purchasing from a company that sells oils specifically for soap making. Reputable suppliers will have scents that are formulated according to the RIFM (Research Institute for Fragrant Materials) standards. This means that the scents are safe for use in bath and body products. You do not want to use fragrances that are meant for candles or potpourri in your soaps, as they could be irritating to the skin.
If you plan on selling your soaps, you want to think about the market you are targeting before deciding which to scent your soap with. If you are going for the natural crowd, then essential oils are your best bet. If you are trying to please a broad audience, then offer both. Some people buy soap for the scent, and don’t necessarily prefer an essential oil over a fragrance oil. Which ever you choose, get the best quality you can for your products!