Solvent/carrier in reeds diffuser

The ingredient of diffuser oil is very simple, basically solvent+essence/fragrance oil. Why not just use fragrance oil to diffuse? Because 100% fragrance oil is too thick to volatile, and the price is too high. Therefore, solvent is required to play the role of dilution and volatilization.

However, the selection of solvent is really a complex problem, which requires a balance between safety and performance. Safety should include physical safety, health safety, and environmental safety, while performance mainly considers volatility. Generally, products with fast volatilization are highly flammable(it’s not safe physically), which is an irreconcilable contradiction. How to balance the two is a test. Here we list several commonly used solvents and their characteristics.

Water

The first should be water, it’s safest, but defects in solubility and volatility. Since the good flame retardancy, it is usually used as the second carrier in combination with other solvents to reduce the flash point of finished products. And it can be said that this is free, the more you add, the lower the price of finished products.

DPM

Dipropylene Glycol Methyl Ether, CAS: 34590-94-8. The most widely used solvent in reeds diffuser, which has the advantages of moderate volatilization, stability, good solubility, and low price. Flammable liquid Category 4 is also relatively safe.

The only thing is that it has a special etheric flavor, this is a critical defect for products with fragrance as the main selling point. Therefore, the amount needs to be balanced.

MMB

Methoxymethylbutanol, CAS: 56539-66-3. It is promoted directly against the DPM, faster volatilization, lower odour, also belongs to Flammable liquid Category 4. But more expensive than DPM. It is the most ideal diffuser solvent if the price can be more affordable.

Isododecane

CAS: 93685-81-5. Oily volatile liquid, insoluble in water, has a low odor, fast volatilization, and high-cost performance. If you want your diffuser with decoration inside, then this is the best option. There is only one concert, it may be fatal if swallowed(from ECHA), and it must be with warning labels.

Alcohol

CAS: 64-17-5. As the solvent with the strongest volatility, it is often used in combination with other solvents to balance the evaporation rate and improve the overall performance of the reed diffuser.

However, it should not be added too much, it belongs to Flammable liquid Category 2, which will lead to the low flash point of finished products and become dangerous, causing trouble in transportation.

DPMA

Dipropyleneglycol methyl ether acetate, CAS: 88917-22-0. It is prepared by an esterification reaction of DPM and acetic acid, and has an ester aroma. This solvent is exempt from VOC Rules, quite safety. Similarly, there is only one warning for the Flammable liquid Category 4 in SDS.

But it diffuses too slowly, must be combined with other fast solvents to improve performance. And due to its oily nature, it is not suitable to mix with alcohol.

Solketal

CAS: 100-79-8. Due to its special structure, it has the title of “universal solvent”. It can not only be used as a solvent, but also as a solubilizer. with the light smell and will not affect the fragrance of the finished.

With the bio-based concept, it is more and more popular. However, it also volatilizes slowly and has to be used with alcohol or other volatile solvents.

Summary

The following are the key parameters of the above solvents：

• Flash point indicates flammability, the lower the value, the bigger risk.
• Vapor pressure indicates volatility, the higher the value, the more volatile.
• LD₅₀ indicates toxicity, the higher the value, the lower the toxicity.

It can be seen from the above table that:

• Physical safety: Water＞DPMA＞DPM＞Solketal＞MMB＞Isododecane＞Alcohol
• Volatility: Alcohol＞Isododecane＞MMB＞DPM＞Solketal＞DPMA＞Water
• Toxicity: MMB＞Isododecane＞DPM＞Solketal＞Alcohol＞DPMA＞Water
• Cost: MMB＞Solketal＞Isododecane＞DPMA＞DPM＞Alcohol＞Water