Formulating Long-Lasting Volcanic Stone Car Air Freshener

Question

Making a volcanic stone fragrance bag for a car.

If I want to make a volcanic stone fragrance bag to hang in a car, and I want the scent to be strong throughout the vehicle and last continuously for over 1 month, what ingredients do I need?

If I marinate the stones with just fragrance oil and keep the lid closed without using ethyl alcohol or dpg at all, is it correct that the scent won't diffuse well?
Please provide advice on what to use. The main goals are: wide diffusion throughout the car and lasting longer than 1 month.

MySkinRecipes Expert · Accepted Answer

To create a volcanic stone fragrance bag for a car that has a strong scent throw and lasts longer than one month, using only fragrance oil is usually not sufficient. Pure fragrance oil is often too dense to evaporate effectively on its own, leading to a weak scent that doesn't fill the car.

1. Correcting the Ingredients

First, it is important to clarify a common misunderstanding regarding "DPG":

Dipotassium Glycyrrhizate (ID: 1070): This is a licorice extract used in skincare to reduce irritation. It is not used for fragrance diffusion.
Dipropylene Glycol (ID: 488): This is the "DPG" used in the fragrance industry. It acts as a solvent and diluent that helps control the evaporation rate of the scent.

2. Recommended Components for Your Goal

To achieve a strong "lift" (diffusion) and long-lasting scent (>1 month), you should mix your fragrance oil with the following:

Ethyl Alcohol (99.9% , 200 Proof) (ID: 706): This helps the fragrance "lift" and spread throughout the car. Without alcohol, the scent will stay close to the stones and won't feel "clear" or "airy."
Dipropylene Glycol (ID: 488): This slows down the evaporation of the alcohol and fragrance, ensuring the scent doesn't disappear too quickly.
DiffuseFix™ (ID: 35246): This is a specific fixative for diffusers. It is highly recommended for your requirement of lasting over a month, as it helps "anchor" the scent molecules.

3. Suggested Ratio & Method

A common starting ratio for soaking stones is:

Fragrance Oil: 40-50%
Ethyl Alcohol: 10-20%
Dipropylene Glycol: 20-30%
DiffuseFix™: 5-10%

Instructions:

Mix the fragrance oil, alcohol, DPG, and fixative together in a glass container.
Place your volcanic stones in a sealable jar.
Pour the mixture over the stones.
Curing (Crucial): Close the lid tightly and let the stones "marinate" for at least 3-7 days. This allows the mixture to penetrate deep into the pores of the volcanic rock.
Once cured, place the stones in your fabric bag and hang them in the car.

By using this combination, the alcohol will provide the initial "punch" to fill the car, while the DPG and DiffuseFix™ will ensure the scent remains consistent for several weeks.