Testing your essential oil blends in a diffuser before using them in soap or other products can be a helpful approach to get an initial sense of how the scents might interact. Diffusing can give you a general idea of the aroma profile and how the different oils blend together.
The way an essential oil blend smells in a diffuser might differ from how it smells in soap or other products. The diffuser disperses the essential oils into the air, allowing you to experience the scent directly and immediately. In soap, the scent might change due to factors like saponification, heat, and interaction with other soap ingredients.
When essential oils are used in soapmaking, they can undergo chemical changes during the saponification process. This can alter their scent profiles. So, while a blend might smell wonderful in a diffuser, it's important to do a small test batch in soap to see how the scent holds up during and after the soapmaking process.