Peppermint essential oil

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eoexpert

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why do you recommend blending peppermint with an oil with a higher boiling/flash point?
DeeAnna is correct regarding vapor pressure and yes, unfortunately this information is not tested/provided by suppliers. Flash point is mentioned in the MSDS/TDS sheets so is a better way to select a lower vapor pressure oil.

Flash point is a measure of the temperature where the vapour created by a liquid ignites readily. For this to occur sufficient vapour pressure is needed near the surface.

Also fragrance oils have a low vapour pressure due to the solvents/plasticizers added to them. But natural Essential Oils dont have any such additives and the vapor pressure will differ a bit. With citrus/mint oils having a VP (lower flash point) due to higher terpene content.

Blending with a high flash point/low VP/ Base note essential oil (or even a fragrance oil) effectively reduces the VP of the blend and hence help the oil last longer.

One thing that some major cosmetic companies do is use fixatives. Which are actually skin safe solvents (for eg, Isopropyl myristate) which are non-volatile and blend with the essential oils before adding to the soap/cosmetics. This helps the fragrance last extremely long comparatively and imparts a longer shelf life to the final product.
 

Mobjack Bay

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Blending with a high flash point/low VP/ Base note essential oil (or even a fragrance oil) effectively reduces the VP of the blend and hence help the oil last longer.

One thing that some major cosmetic companies do is use fixatives. Which are actually skin safe solvents (for eg, Isopropyl myristate) which are non-volatile and blend with the essential oils before adding to the soap/cosmetics. This helps the fragrance last extremely long comparatively and imparts a longer shelf life to the final product.
On the recommendation of another SMF member, and after reading about the importance of VP and head space when making perfume, I started storing my EO scented soaps in closed cardboard boxes at about the 6-8 week mark. After 4-6 months, the soaps still smell wonderful. Have you tried using isopropyl myristate in cp soap, or can you point me to a source for further information on a method?

ETA: I found a KOH SAP value (202-212) in the LotionCrafter specification sheet, here. Does saponification affect the fixative property?
 
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Zany_in_CO

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One thing that some major cosmetic companies do is use fixatives. Which are actually skin safe solvents (for eg, Isopropyl myristate) which are non-volatile and blend with the essential oils before adding to the soap/cosmetics. This helps the fragrance last extremely long comparatively and imparts a longer shelf life to the final product.
Good to know! That's a new one on me! Thanks!
Thank You.gif

ETA: Can you please tell me :videovisit: where I might find information on using IPM to "fix" EOs in CP/HP soap? Perhaps starting a new thread on the subject?
 
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Marsi

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Interesting replies
thank you 🥰

i found a few vapour pressure information pages at the goodscentscompany.com
two examples, peppermint oil (flash point 160F, vapor pressure 0.3 mmHg @ 25C) and a known anchor (scent only) oakmoss phenol (flashpoint 275F, VP 0.01 mmHg @ 25C)
Peppermint: The Good Scents Company - Aromatic/Hydrocarbon/Inorganic Ingredients Catalog information
Oakmoss phenol: The Good Scents Company - Aromatic/Hydrocarbon/Inorganic Ingredients Catalog information

On the recommendation of another SMF member, and after reading about the importance of VP and head space when making perfume, I started storing my EO scented soaps in closed cardboard boxes at about the 6-8 week mark. After 4-6 months, the soaps still smell wonderful.
practical and simple
thank you
😍

To add
i have seen local brands of expensive cold process soaps sold in lightly sealed cardboard boxes (no sniffy holes or shrink wrap plastic)
they also keep their scent very well

Because many people think the flash point temperature is related to how fast the fragrance evaporates. In other words, a scent with a lower flash point supposedly will evaporate a lot faster.

The vapor pressure is the property that does predict a chemical's tendency to evaporate quickly or slowly. High vapor pressure = fast evaporation.

Unfortunately, vapor pressure info (and boiling point info) for fragrances is often hard to find. Flash point temperatures are easy to find, however, because sellers have to know the F.P. temps to ship these chemicals safely.

Awhile back, I compared the flash point temperatures and vapor pressures of 55 fragrance oils to see for myself whether there was a useful relationship between F.P. and vapor pressure or not. The fragrance oils had a wide range in the flash point temperatures (from about 130 F to over 200 F), but there were only small differences in their vapor pressures. In other words, a fragrance that has a high flash point temperature doesn't evaporate any much faster or slower than one with a low F.P.

Another tidbit that I thought was interesting is all of these fragrances have vapor pressures that are at least 20 times lower than water and 35 times lower than ethyl alcohol (ethanol, grain alcohol). I (and I'm sure others) have the perception that fragrances evaporate really fast ... but they really don't.
would the conclusions you drew from testing fragrance oils apply equally to essential oils?

DeeAnna is correct regarding vapor pressure and yes, unfortunately this information is not tested/provided by suppliers. Flash point is mentioned in the MSDS/TDS sheets so is a better way to select a lower vapor pressure oil.

Flash point is a measure of the temperature where the vapour created by a liquid ignites readily. For this to occur sufficient vapour pressure is needed near the surface.

Also fragrance oils have a low vapour pressure due to the solvents/plasticizers added to them. But natural Essential Oils dont have any such additives and the vapor pressure will differ a bit. With citrus/mint oils having a VP (lower flash point) due to higher terpene content.

Blending with a high flash point/low VP/ Base note essential oil (or even a fragrance oil) effectively reduces the VP of the blend and hence help the oil last longer.

One thing that some major cosmetic companies do is use fixatives. Which are actually skin safe solvents (for eg, Isopropyl myristate) which are non-volatile and blend with the essential oils before adding to the soap/cosmetics. This helps the fragrance last extremely long comparatively and imparts a longer shelf life to the final product.
i could not find a soap with isopropyl myristate as an ingredient in australia - could you please provide me with an example?
i did find a website with vapour pressure information - i put that at the top of my post for you
 

ResolvableOwl

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Isopropyl myristate is an ester, just like oils are. It won't survive CP saponification, but is cleaved by lye to give isopropanol (volatile) and myristate soap (like coconut and a few other oils do). It has no chance to have any advantage over any other excess oil (unless added into HP as part of post-cook addition).

I guess that's why people aren't wasting it for lye-based products.
 

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